In certain areas of processing, your installation might need to customize its MVS™ system to an extent not available through standard options, such as initialization parameters and operator commands. IBM® provides installation exit points for this purpose.

There are installation exit points located throughout the MVS system code. When an exit is invoked, the system passes control to an IBM-supplied routine that might or might not perform actual processing. When you provide an exit routine, control passes to that routine, which does its special processing. At the end of the user routine, control returns to a specified point in the system code.