TSO/E provides two exits you can use to customize CLIST processing. One exit is for installation-written built-in functions, and the other is for installation-written statements.

The exit for installation-written built-in functions enables you to define and process your own built-in functions. The exit receives control each time TSO/E encounters a CLIST built-in function that it does not recognize.

The exit for installation-written statements enables you to define and process your own CLIST statements. You can also use this exit to do your own processing of TSO/E commands. This exit receives control each time TSO/E encounters a TSO/E command or an unrecognized statement in a CLIST.

For more information, see Customizing CLIST and REXX processing.