JCL symbols differ from system symbols in that you must define them in started task JCL before you can use them in that JCL. The JCL symbols that you define are valid only for the current job. Conversely, there is no need to define system symbols; they are either defined to MVS™ or defined by your installation, and you can use them in any set of started task JCL.

The rules for coding JCL symbols are the same as for coding system symbols. You can code system symbols anywhere in started task JCL that you code JCL symbols.

This section explains how to define, nullify, and use JCL symbols in JCL.