IBM Student Mainframe Challenge Russia

Part OneTime to complete – about an hour

The goal of Part One is to learn how to use an IBM System z mainframe having not used one before.

Welcome to the 2010 Mainframe Challenge!You'll be joining our team of mainframe

programmers to learn some skillsthen prove yourself above the other

contestants! Good luck!

Hi, my name's Jim. Welcome to theteam! I've been here for a fewmonths already, so I'll be able to

offer some help and advice aboutusing the mainframe, and about

what the contest requires.

Psst! The boss told me earlier what theprizes for each part will be, so listen up!

Part One: a t-shirtPart Two: a knapsack

Part Three: a bookreader!

I'll set some tasks and questions throughoutthe contest to see how you're getting on.

There will also be prizes for the fastestcontestants in each part

(if you answer correctly, of course!)

So, you want to learn the mainframe? Become a whiz with z/OS? Make millions touting your

desperately sought-after skills all over the world?

First things first, let's teach you how to log on to the mainframe. (Everyone has to start somewhere.)

The software

In order to access the mainframe you'll need some software that will allow you to connect to it, and will

be able to display the z/OS interface. We call it a 3270 terminal emulator (snappy, huh?) - they are

available for multiple platforms.

Note: If you're planning to double-check your progress by following the screenshots in

these instructions, be aware that they were all taken on a Windows machine. If you're

running a different operating system things may look slightly different, but not much.

If you're using Windows...Go to http://www.tombrennansoftware.com/download.html and download the Vista V1.27.exe

file. Install it by running the .exe file and following the installation instructions.

If you're using a Mac...Go to http://brown.edu/cis/tn3270/ and install the latest available version.

If you're using Linux...You'll need to install the following package: x3270 -port1023 (available from

http://x3270.bgp.nu/)

After installation

Everyone got their emulator installed? Good!

The next step is to start it running. (Predictable, I know.) The default location after a Windows

installation is Start Programs Vista tn3270 Vista Standard session. → → →

You might see this error:

Don't worry about it, just continue. Now we can set up your emulator and connect to the mainframe.

Configuration

➔ Configure your emulator as shown below.

(Windows users: from the menu bar in Vista Session A, select File Reconnect Ask.)→

The Host IP Name is 129.35.161.131 and the IP Port is 23. These values point towards the z/OS

system you'll be accessing.

➔ Fill in these two values, and click Connect. If all is well, you should see this:

Congratulations, you have connected to the mainframe! Don't rest on your laurels yet, there's more

to come.

A z/OS primer

Now's a good time to give you some background information about z/OS, before you dive into it.

z/OS is an upgrade of what used to be called OS/390. Both of these operating systems are

an evolution of MVS (which stands for Multiple Virtual Storage). General mainframe literature still contains many references to these terms. When you're connected to the

mainframe, you will find that things are a bit different to what you are used to...

A world where Ctrl == Enter

A number of keys on your keyboard don't have the same function as they would in your usual operating system. For example, the biggest one to remember is that to enter a

command, you need to press Ctrl, not Enter! (That's the right Ctrl only, not the left

one.)

In the z/OS world, the Enter key is a navigation control, and will move the cursor down to

the next form field on the screen.

(I should point out, for maximum confusion, that what we typically call “Enter” is

technically called Return (as in “carriage return” on typewriters – remember typewriters?

Oh, never mind), and to be fair, this is exactly what that key does on z/OS – moves the

cursor down a line. Additionally, the Enter key found on a numeric keypad also serves,

like right Ctrl, to enter a command. I shall be referring to Enter when I mean ↵ and to

“enter” when I mean Ctrl.)

Is everything as clear as mud now? I've summarised the common differences below:

Action Key on mainframe

Key on other O/Ss

Notes

Enter a command Ctrl Enter

Scroll up one page F7 Page Up

Scroll down one page F8 Page Down

Exit current screen F3 Esc Esc is the closest equivalent, and not always used

Scroll left one screen F10(none)

Isn't that great? This is extra functionality only available on z/OS!Scroll right one screen F11

Change to Insert mode Insert Insert You get this one for free

Move cursor to next field Tab Tab This one too

Move cursor to first field on next line

Enter (none) This is what will happen when you forget about Ctrl!

However, ultimately it depends on the emulator you're using. These are the common settings, you should be able to find out the mapping that your emulator uses if it's different.

Now that you know all that, let's put it into action by logging on...

Logging on

Remember where you were? The mainframe welcome screen?

You should have a cursor (looking like this: _ ) after a prompt (looking like this: ==> ) saying

SELECT APPLICATION (looking like this: SELECT APPLICATION ).

➔ Type TSO at the prompt and enter.

You will see a big black screen with a red message saying: IKJ56700A ENTER USERID. Much like this,

in fact:

➔ Enter the user id that you have been allocated.

For the UK contest it will be 7 characters long, and start with UK. For the z/Master 2010 contest it will start with RUS. From now on whenever I say RUSxxxx or UKxxxxx, substitute your own user id.

...that was a test...did you remember to hit Ctrl

instead of the Enter key?If not, don't worry, just press Ctrl now.

And remember, from now on when I say “enter”, press Ctrl!

Now press Enter. (You know I mean Ctrl, right?)

You will be taken to this screen so that you can enter your password (which is the same as your user id

the first time you log on):

➔ At the password prompt ( ==> ) type in your user id and hit Ctrl. You will be

prompted to choose a new password.

➔ Enter your new password twice (followed by Ctrl each time).

At the bottom of the logon screen, there is a note to say you can press PF1 or PF13 for

help. PF or “program function” is the old name for F or “function” keys. So, when there is

an instruction to press (for example) PF3, the key you want is F3 on your keyboard.

Passwords in z/OS have a maximumof 8 characters, but apart from

that you can go nuts.

You will be taken to the ZEUS welcome screen:

(I know what you're thinking. Could be more welcoming, right?)

Notice at the bottom of the text you see this: *** The three asterisks mean that the system is

waiting for your input to continue on its way, so press Ctrl to continue.

Ahh! This is what we've been waiting for!

This is ISPF. This is where the magic happens. This is your point of control.

(While we're on the subject of control, hit Ctrl to clear the copyright message out of the way.)

You are officially logged into a z/OSmainframe, and you've successfully

completed the first three steps of Part One.

Congratulations!

Customise your environment

In ISPF you can edit settings to make the environment your own. Let's try it out by moving the

command line from the bottom of the screen to the top of the screen (this is what all the pro's do).

So, you've got your cursor on the command line. Enter 0 – this will take you through to the ISPF

settings menu:

On this screen, practise navigating through the

menu by pressing the Tab key repeatedly. You'll see

the cursor moving through every field on the

screen.

Tab Tab

Tab Tab

Tab Tab

Tab

Tab

Tab Tab

Now try pressing the Enter key repeatedly. (Yes, I

actually mean Enter this time!) You can see the

cursor going to a new line each time, seeking out

the first field on each line.

Enter

Enter

Enter

Navigate to the field (that looks like this: / ) beside 'Command line at bottom'. Delete the '/' using

the delete key and press enter (yeah, yeah, I mean Ctrl).

See the command line jump to the top of the screen!

Oh F3, we sing of thee

The F3 key is another useful navigation command because it exits the screen you're in and goes to the

previous screen, sort of like the Back button in an Internet browser. If you hit it twice from here...

...WAIT! Don't do that!

...you'll find yourself at the TSO READY prompt. (If this happens, just enter ISPF again.)

Logging off

In fact, this is what you want to do when you want to log off; F3 back to the TSO READY prompt and

then type logoff.

You should never just close the connection windowwithout logging off properly, else you may find

yourself locked out of your account!

When you want to log off, if you have done any extensive work during your session, you may be

presented with a further screen (much like the one below):

If you come across this screen, select Option 2 (“Delete data set without printing”) and press

enter. Then you can log off as described above.

If you get locked out of your user id, maybe because yoursession was cut off unexpectedly, wait 10 minutes for the system to drop the user id, and then try again.

If you are still having problems, contact shane_babey@hotmail.com on MSN, he'll fix your problem if he's around.

Use ISPF to locate the data sets created for your ID

Start at the ISPF primary menu, and go for option 3:

Option 4 on the next screen is called Dslist and is short for “Data set list”.

➔ Type 4 and press enter.

Now we can get to examining the data sets that have been created for your id – on the next screen

there is a field called Dsname Level.

➔ Navigate to this field (with the Enter key, remember?) and type in your user id

RUSxxxx and press enter. (Ctrl!)

You'll be presented with a list of all the data sets owned by your id.

Browsing the members

New worlds. Strange terms. “PDS”. That stands for Partitioned Data Set, and it's like a folder or

directory on other operating systems.

A PDS contains “members” (so I guess a PDS is like a club?). Members are like files on distributed

operating systems.

Let's look at the members inside the data set called RUSxxxx.PDS.CNTL.

➔ Tab your way down until the cursor is next to it and type b (for browse) and press

enter.

You'll then see (hey presto) a list of members!

So remember, a partitioned data set (folder) contains members (files). Easy.

All of the members you see are empty (oh, except for the top one, called JOBSTMT, which actually

contains some JCL. We'll get to that later).

You can browse (look at) members in the same way that you browsed the PDS – by

Tabbing down until your cursor is next to the one you want to look at, and then typing b

and pressing enter.

Why don't you try it?

➔ Browse a couple of the members. Oh, go on.

Creating new files

You can probably tell that creating a file on the mainframe is a more involved process than

on Windows or Unix. Those operating systems use what's called a bitwise filesystem,

whereas z/OS typically uses a record-oriented filesystem.

In a bitwise filesystem, like on Windows or Unix, a file is just a sequential collection of bits,

and there is a special character to tell the computer where a line ends and the next one

starts. Often this special character is \n.

In a record-oriented system, instead of having a stream of bits and a special end-of-line

character, each line in a file is 1 distinct record and files are organised on the disk into

contiguous records (stored consecutively on the disk). Because of this property, you define

the sizes and attributes of the records so there isn't any need for a special end of line

character. This helps to conserve system resources, which is a recurring theme in z/OS!

Mainframes can also support special bitwise filesystems called HFSs and ZFSs.

What else is different about z/OS? It has very rich support for controlling resources, and this

spills over into the filesystem. What this means for you is that when you create a new

dataset, you have to tell z/OS how big it can grow, as well as how its records are set up on

the disk.

You might think that this seems, well, cumbersome compared to desktop operating systems.

After all, you don't need to define parameters for every file or folder on your PC! But the

reason that z/OS needs to track every file is to keep the amazing disk access speeds of the

mainframe. Suppose you had a rogue program with some bug that makes it keep writing out

to disk. If we left this unchecked on a mainframe, you could find terabytes of data written

out, filling up your disks. Before you realised what was happening, it would be too late. Not

such a big deal if you're downloading music on your computer, but if this happened to a

bank or an airline while processing millions of transactions, it could be crippling!

That's why the mainframe works the way it does. It's an important consideration in large

systems thinking!

All this also means that something as simple as creating a new PDS is a very customisable

task. It's important to do this this way when you have thousands of users accessing a single

machine, and millions of transactions per second!

Allocate a partitioned dataset extended (PDSE) using ISPF panels

➔ Now, press F3 until you are back at the ISPF primary option.

➔ Select 3 (utilities), and then 2 (data set) on the next screen.

You'll be taken to the following screen:

➔ On the option line (at the top), type A (for Allocate a new data set).

Here you also need to give the name of your new dataset. Datasets are named with identifiers 1-8

characters long, and separated by dots, like this: RUSxxxx.ZOS.PARTONE.

The system will automatically assume that you want the first identifier to be your user id.

➔ In the field which says Data Set Name, type ZOS.PARTONE and press enter.

Typing 'RUSxxxx.ZOS.PARTONE' wouldresult in the same thing as ZOS.PARTONEbecause without quotes, the system will

automatically add your user id to the start.With quotes, it won't, so you have to

type it yourself.

The next screen is the one you use to customise your new dataset.

(See how it says More: + in the top right hand corner? That means that the page is too large to fit on

one screen. Use F7 and F8 to Page Up and Down the page.)

➔ Specify the following attributes for your PDSE:

It should be allocated in tracks (TRKS)

It should have a primary quantity of 1, and a secondary quantity of 1.

The record format should be FB (fixed block), and the record length should be 80. The

block size should be 32000. The data set name type should be LIBRARY (this tells the

system that you are creating a PDSE).

➔ Set these values appropriately on the screen.

(Any fields not mentioned above can be left blank or with the default that was already there.)

See the next screenshot for how it should look:

➔ Hit enter!

Notice the message in the top right hand corner: Data set allocated. Success! You've successfully

created a data set on the mainframe!

So what types of datasets can I make anyway?

You've just made a PDSE, Partitioned Data Set Extended, and as the “extended” implies, the

PDS was its predecessor. PDSEs are very similar to the PDSs, with a few internal

improvements.

There is another type of dataset called a sequential dataset. A sequential dataset is like a

flat file; it behaves the same way as a a member of a PDS would. You can edit a sequential

dataset directly, and it doesn't hold any members.

Whenever you see a message in the top right hand corner like that,you can always hit F1 for help

about the message.

Populate your new PDSE with a member

A member could be anything – program code, program output, binary data, or flat text.

➔ F3 all the way back to the ISPF Primary Option Menu.

➔ Select option 2 (Edit).

We'll name the member after its creator - you.

➔ Put the name of the dataset in the “Data Set Name” field, then the name of the new member in brackets afterwards. Like this: ZOS.PARTONE(JIM)

A member's name can only be up to 8 characters long though, so you may have to shorten your name!

Press Ctrl and a new member will be created and opened in the text editor.

You've made a dataset, but at the moment there isn't anythinginside it! Let's create a memberwith some text in.

Note that ISPF assumes you want “RUSxxxx.” put on the front of your dataset name, so

the member will actually be put in RUSxxxx.ZOS.PARTONE.

Enter three lines of text into your new dataset member

Now you're in the ISPF text editor, looking at a blank member:

➔ Move your cursor to the first line of the blank space (under the ==MSG> lines).

The first 6 columns, shown with red ****** at the top, will show line numbers when the

member has some stuff in it. You can also enter line-specific commands such as copy, hide,

delete and insert in this column; by typing your commands over the top of the line

numbers. These columns aren't actually part of the member, so start at the left of the blue

******** columns when you're typing data in.

Later on I'll be using an automated program tocheck whether you've followed Jim's

instructions correctly. It's probably best if youdon't write more than 40 characters per line.Also, type something different on each line.

Later on it'll become clear why.

➔ Now type in three lines of text.

If you've done something wrong, you can type CAN (short for CANCEL) on the command line, and it'll

return to the Edit Entry panel you were at before. If you do this, the member won't have been

created, and you can press Ctrl on the Edit Entry panel to do the last step again.

You can enter HELP on the command line for more information about the ISPF editor.

The screen should look something like this:

➔ To save this, type SAVE on the command line.

After you've saved it, or if you pressed Ctrl while typing the text, you may notice that the

blank lines have gone, and the editor says:

******** Bottom of Data ********

To preserve system resources, the ISPF editor has made the member exactly 3 lines long.

The member consists of 3 records on the filesystem, since each line is 1 record.

To insert more lines, check the next section!

Use the ISPF editor to manipulate the text

This is where you put editor commands – just type them over the top of the line numbers in the

command column:

i – insert lines after current line.

Can be followed with the number of lines to insert (e.g. i2)

➔ Insert two lines by putting i2 in the command column on the third line, as shown in

the screenshot.

➔ Now press Ctrl.

Two blank lines have been created at the end of the member.

Now let's practice some simpleISPF editor commands; they'll be your basic tools for editing all the

different members you'll comeacross during the contest!

Instead of writing more text into these inserted lines, let's copy the text we already have.

c – mark lines for copying. Can be followed with the number of lines to copy (e.g. c2)

cc – mark a block of lines for copying. Must be put on two separate lines, and these will be

included in the block of lines to copy.

a – insert marked line(s) after the current line. Can be followed with the number of times

to repeat the marked line(s)

b - insert marked line(s) before the current line. Can be followed with the number of times

to repeat the marked line(s)

Notice that instead of line numbersnext to these new lines, there aredots instead. This means they'retemporary lines which will beremoved if you don't put anythinginto them before hitting Ctrl again.

As shown in this screenshot,

➔ Put cc on the first and third lines to copy all the text you already have.

➔ Put a50 on the first blank line to paste the text 50 times after the end of what you've

written.

➔ Press Ctrl to execute these commands!

The member should look something like this:

d – delete current line. Can be followed with the number of lines to delete (e.g. d999 to

delete pretty much everything)

dd – delete a block of lines. Must be put on two separate lines, and these will be included

in the block of lines to delete.

Now let's repeat the first line of text 10 times. To do this, use the repeat command:

r – repeat the current line immediately below. Can be followed with the number of lines to

repeat (e.g. r5)

rr – repeat a block of lines. Must be put on two separate lines, and these will be included

in the block of lines to repeat.

➔ Type r10 on the first line and press Ctrl.

Did it work?When copying lines, you have tospecify both where they're comingfrom (c or cc) and where they'regoing to (a or b) before you pressCtrl, otherwise it'll say:MOVE/COPY is pending

The line is repeated, and the line numbers are incremented to match.

Nearly done!

The last thing to do is to add a line at the bottom of the member to say what size t-shirt you'd like if

you win this first part of the contest!

➔ Type BOTTOM on the command line and press Ctrl to get to the bottom of the file.

➔ Insert a line stating the size t-shirt you want!

(Likewise, TOP will take you... you can probably guess where.)

Well done!You've learned how to log into amainframe, how to browse and

create datasets, and how to makeand edit your own dataset.

Next we'll run an executableprogram with your dataset as the

input.

Why doesn't it scroll automatically?

One of the unfamiliar things about the ISPF editor is that it doesn't automatically scroll as you type, like most PC editors do. There's a reason for this: efficiency!

The terminal on your screen hardly does any processing, just displays what it receives from

the mainframe (which is doing all the work). In the non-mainframe world, when you are using an editor that scrolls in real-time, going through the network to a server, you are

always sending data back and forth to the server (for just about every key stroke). With mainframes (and the emulator you're using), data is only sent to the mainframe when you

hit enter or an F key. This saves a lot of traffic. When you have upwards of 10,000 or more folks working at the same time, those few bytes on the network can mean big savings.

➔ Press F3 to exit the editor; the file will automatically be saved.

If you ever want to quit without saving, typing CAN or CANCEL on the command line will do the trick.

Run an executable against your new dataset member

➔ From the ISPF Primary Options screen, choose option 6 – Command.

This screen lets you enter TSO commands from ISPF.

The REXX exec code is stored in a dataset called ZOS.CONTEST.REXX(COUNT) – COUNT is the name of

the source code member. We'll run it and use the member you just created as the input.

➔ Enter EX 'ZOS.CONTEST.REXX(COUNT)' 'xxxxxx' (where xxxxxx is whatever you named

the member you created).

EX is the TSO command to execute a program.

The program will begin, and output some messages:

The program we're about to run iswritten in a language called REXX.REXX originated on the mainframe,

but has been ported to a bunchof other platforms too. I like using

REXX, it's simple and readablebut still powerful.

➔ Press Ctrl again to clear the output and return to the ISPF command shell where you ran the

program from.

The program has finished executing, so we can go and see what it did.

Remember that *** means themainframe is waiting for you to

press Ctrl. It'll continue runningthe program when you do.

The ISPF command shell keepsa list of commands you've enteredrecently. Put the cursor on one ofthese commands and press Ctrl

to save time!

Here's a cool trick to bypass the ISPF Primary Option menu...

➔ Enter =3.4 on the command line instead of pressing F3

This is the same as choosing 3 from the Primary Option Menu, then choosing 4 on the next screen.

Shortcut! On any command line, enter = then a menu option, with further options separated

by . to jump straight there! For example, in the last few sections you've been to: =2, =3.4

and =6.

➔ Enter your user id on the Dsname Level field to look at your datasets.

Remember how I told you that if you don't usequote marks when specifying the data set name,the system will automatically add your user id to

the start? Well, the data set list utility 3.4 isthe only panel in the utilities menu (3) that

doesn't do that.So, you'll always have to type the full data setname here, including your user id at the start.

➔ On the next screen, put an E (for edit) beside the dataset RUSxxxx.ZOS.PARTONE to look

inside it.

You should find a new member in there, named after your user id.

➔ Put an E beside it and press Ctrl to have a look.

The REXX exec counted each occurrence of the different lines you put in the member you

created (plus your t-shirt size), and wrote the results to this new member.

If any of your 3 original lines of text were the same as each other, the REXX program won't have

worked correctly, since it should come up with the result shown below – 61, 51, 51 and 1. If this

happened to you, go back to page 21 and start over with a member with 3 lines of text!

In this member is the output ofthe COUNT program that you just

ran. I think it's fairlyself-explanatory!

➔ Do as the man says! Enter SAVE on the command line

After you save the member, you can verify that it was saved correctly by the white message in the

upper right hand corner: “Member RUSxxxx saved”.

➔ F3 back to the previous screen

The prompt tells you that the member was edited. This happens even if you exit by putting CANCEL on

the command line, but in that case it wouldn't be saved.

I want to see when you completedthis step properly, so please enter SAVE

on the command line. This willtimestamp the member so I can seeif you're in the running to receive

a t-shirt!

While browsing a dataset:

Put E in the left-hand column next to a member and press Ctrl to edit it in the ISPF text

editor.

Put B in the left-hand column or just put the cursor next to a member and press Ctrl to

browse it.

This program will let you know whether you've been successful!

The last thing to do is to runanother exec – you can rememberhow to do that, right? Use this:

EX 'ZOS.UK.CONTEST.REXX(CHKPART1)''RUSxxxx.ZOS.PARTONE'

Congratulations! You've finished allthe steps for Part One! If you're oneof the first 200 successful winners,I'll send you a t-shirt in due course.

You've accomplished a lot so far; not only can you create datasets and members on the

mainframe, you can also run programs and generate output etc.

It might be worth putting some of this onyour CV – hands-on mainframe experience

certainly sets you apart from other job seekers!

There are lots of companies likeours who use a mainframe for

large-scale data operations. The current generation of mainframe

programmers are reachingretirement age, so large employers

will be seeking mainframe skills.

For more background and current information on mainframes and how widely they're used in business,

check out these sites!

IBM System Z homepage

http://www.ibm.com/systems/uk/z/

IBM Academic Initiative for System Z

http://www.ibm.com/developerworks/university/systemz/index.html

IBM Academic Initiative System z program (RUS) :

http://www.ibm.com/ru/software/info/students/members/

• “All of the top 25 world banks run their businesses of mainframes.

• 23 of the top 25 global retailers run their mission-critical applications on a mainframe and rely

heavily on enterprise systems-skilled employees.

• 9 out of the top 10 global life/health insurance providers process their high-volume

transactions on a mainframe.”

In Part Two we're going to be doingsome more challenging tasks,

including compiling and runningprograms, and using some of IBM's

biggest and best applications!See you there!