Job Control Language

Job Control Language (JCL) is a scripting language used on IBM mainframe operating systems to instruct the system on how to run a batch job or start a subsystem.^[1] The purpose of JCL is to say which programs to run, using which files or devices^[2] for input or output, and at times to also indicate under what conditions to skip a step. Parameters in the JCL can also provide accounting information for tracking the resources used by a job as well as which machine the job should run on.

There are two distinct IBM Job Control Languages:

one for the operating system lineage that begins with DOS/360 and whose latest member is z/VSE; and
the other for the lineage from OS/360 to z/OS, the latter now including JES extensions, Job Entry Control Language (JECL).

They share some basic syntax rules and a few basic concepts, but are otherwise very different.^[3]

The VM operating system does not have JCL as such; the CP and CMS components each have command languages.

^ "Every job submitted for execution ... must include JCL statements" -- ibm.com
^ and many more complex details, such as whether the file is to be retained or deleted, the maximum disk space to which it can grow, the name of a tape to be pre-mounted
^ Ashley and Fernandez, Job Control Language, p. 1.

[1] "Every job submitted for execution ... must include JCL statements" -- ibm.com

[2] y more complex details, such as whether the file is to be retained or deleted, the maximum disk space to which it can grow, the name of a tape to be pre-mounted

[3] Ashley and Fernandez, Job Control Language, p. 1.

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