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Let’s start with JCL

You probably know PHP, Java, C, and lot of other programming languages, but what about JCL ? No, it’s not about Java, it’s about Job Control Language a scripting language used on mainframe to instruct the system on how to run a batch job. It is possible to submit JCL for batch processing or directly by to start a JCL procedure (PROC). JCL is very important to create, check, correct and run the daily batch workload.

It’s easy, you have three basic  statements:

• JOB: Provides a name (jobname) for the batch.
• EXEC: Provides the name of a program to execute.
• DD: For Data Definition, provides inputs/outputs to the program.

Let’s see a JCL example:

//MYJOB     JOBTES 1
//MYSORT    EXEC PGM=SORT
//SORTIN    DD DISP=SHR,DSN=SUP01.TAB.TEST
//SORTOUT   DD SYSOUT=*
//SYSOUT    DD SYSOUT=*
//SYSIN     DD *
SORT FIELDS=(1,4,CH,A)
/*

Now, try to understand what’s happen here.

• MYJOB is the jobname associates to the workload, here it’s “JOBTES”.
• MYSORT is the stepname, which ask the system to execute a program called “SORT”.
• SORTIN is the program input, here with the DSN (Data Set Name) SUP01.TAB.TEST, and the dataset can be shared (DISP=SHR).
• SORTOUT is the SORT program output.
• SYSOUT specifies to send system output to JES (Job Entrey Subsystem), but it’s also possible to send the outpu to a dataset.
• SYSIN tell the SORT program which fields of the SORTIN data records are to be sorted.

Enough for the moment, JCL is quite hard at beginning !

Tags: JCL, z/OS

Mapping Unix to z/OS concepts

Unix and z/OS have common points, but they have very different concepts.

With Unix we talk about “boot” a system, with z/OS we talk about IPL (Initial Program Load). IPL is a hardware function, not a program run on the system. The IPL function reads 24 bytes from an operator-specified or pre-configured device into memory starting at location zero.

With Unix we talk about “files”, with z/OS we talk about Datasets. Datasets are not unstructured streams of bytes, but rather are organized in various logical record and block structures determined by the DSORG (data set organization), RECFM (record format), and other parameters. Programmers utilize various access methods (such as QSAM or VSAM) in programs reading and writing data sets, their choice depending on given data set organization.

With Unix we have the system configuration data in the /etc, with z/OS we have PARMLIB which control how the system IPLs and how address spaces behave.

With Unix we have the Shell scripts, Awk, Perl,.., with z/OS we have REXX execs and CLISTS.

With Unix we have threads which are supported by the Kernel, with z/OS we have tasks or a service request block (SRB).

With Unix we edit data with Vi, emacs, sed, with z/OS we use ISPF, which is more powerful than you can think..

With Unix we have the ps and kill command, to view processes and kill them, with z/OS we have SDSF who allow to view and terminate a job.

Tags: Unix, z/OS

SQL tuning teleconference on September 1 from IBM

A new teleconference from IBM on SQL tuning for DB2 on system z coming on Tuesday, September 1, starting at 3pm (UTC). Aim for application programmers, application development managers, database administrators and database managers,  with an intermediate technical level. With the growing of the IT infrastructure, we must find how can we deliver a scalable, reliable, available and highly secure database infrastructure, in a cost-effective data server environment !

The case study will explain:

• How the project was started
• Which techniques and strategy were used
• How follow-up was done
• What investments where made
• What was the return on investment

The speakers are Surekha Parekh, DB2 Market Manager/Strategist, IBM Software Group and Kurt Struyf, Senior Consultant from Competence Partners.

You can register at SQL tuning: the necessity, the benefits, a business case.

Tags: DB2, IBM, system z, teleconference

z/OS 1.11 available on september 25, 2009

The last version of the operating system for system z has just been announced officially. z/OS 1.11 will focus on technologies that make the success of the mainframe, hardware virtualization for performance improvement, very high availability, security, flexibility, and ease of administration.

IBM took the opportunity to launch a new product called z/OS Management Facility, which will allow programmers to manage and administrate a mainframe with more ease, on the daily z/OS operation.

z/OS 1.11 and z/OS Management Facility will be available on Septembre 25, 2009

Tags: system z, z/OS