For your program to execute on the computer and perform the work you designed it to do, your program must be processed by your operating system. Your operating system consists of a base control program (BCP) with a job entry subsystem (JES2 or JES3) and MVS/DFP installed with it.
For the operating system to process a program, programmers must perform certain job control tasks. These tasks are performed through the job control statements, which are listed in the first chapter. The job control tasks are introduced in the second chapter as well as introductory information about JCL. The charts in the third chapter divide these tasks into detailed subtasks.
The tasks are:
- Entering jobs
- Processing jobs
- Requesting resources