Job Control Language

Written by Shirley Parker
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Job Control Language (JCL) is used to communicate with operating systems on IBM mainframes, including the MVS, OS/390 and z/OS. Like every other language, rules of syntax must be followed and users need to learn to code JCL in order to run jobs or batches and to use batch utility programs. A Sort / Merge function is also commonly used within JCL.

JCL statements spell out which data sets to access, which data sets to create, the resources to allocate, and the programs to be run using all this information. An auxiliary program within the operating system is called JES or Job Entry Subsystem. JES statements provide additional information to increase efficiency. Batches, such as print jobs, run in the background without needing the user to intervene. When the operating system is allocating time and space from its resources, foreground jobs that require user interaction are given priority.

A student doesn't need to be a programmer to learn JCL, though that is always a help to gain a greater comprehension. Other employees who can benefit from knowing JCL might be operators, analysts and support staff, or anyone who needs to understand the related workflow. An individual documenting procedures would need to be able to follow specific steps in order to put together a flow chart, for example.

Where Do People Learn JCL?

Universities still teaching about mainframes generally have their own instruction manuals for JCL that include an introduction to writing JCL statements and all the coding information that a student will need. IBM manuals are also available within the IT department. Some commercial schools also offer courses (average length three days), which may have some prerequisites. A student may also be able to self-study from books.


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