Meaning – The term job control language, refers to the control language used to identify a job to an operating system and to describe the jobi?s requirements.
More specifically, the purpose of JCL is to say which programs to run, using which files or devices for input or output, and at times to also indicate under what conditions to skip a step.
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).
Example of usage – “Many batch jobs require to set up, with specific requirements for main storage, and dedicated devices such as magnetic tapes, private disk volumes, and printers set up with special forms. JCL was developed as a means of ensuring that all required resources are available before a job is scheduled to run.”