Three basic steps are taken to process a COBOL program:

  • Compilation
  • Link-editing
  • Load module execution

The input to the compilation step is called the source program. The output from the compilation step is called an object module, which is the input to the link-edit step. The output of the link-edit step is the load module, which is one or more object modules with all external references resolved. The load module is the program that is executed in the go step. If the loader is used in place of the linkage editor, the last two steps (link-edit and load module execution) are combined into one step.

Each step is called a job step-the execution of one program. Each job step may be executed alone or in combination with other job steps as a job—an application involving one or more job steps. Hence, a job may consist of one step, such as COBOL compiler execution, or of many steps, such as compiler execution followed by linkage editor execution and load module execution. You define the requirements of each job to the operating system through job control statements.

The following statements show general job control language for a compilation job step.

job control language for a compilation job step

job control language for a compilation job step

You can modify and customize these JCL statements to suit your needs. More about that is described in the JCL section.

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