TSO/E provides exit points for many TSO/E functions and commands. An exit point is a specific point in a function's or command's processing where the function or command invokes an exit routine if one exists. You write an exit routine to perform special processing and customize how the function or command works. When your exit routine completes its processing, it returns control to the function or command that invoked the routine.

Exit routines let you change default values or actions or extend a TSO/E function. You can write an exit routine to change default processing, change the information a user specifies on a command, or extend the processing capabilities of a TSO/E command or function. TSO/E commands base their processing on input that users enter when they issue the command. You can write an exit routine to change the operands the user specified and therefore change the command's processing. You may also want to restrict users from using certain operands of a command.

For some functions or commands, TSO/E provides a default exit routine. If you do not write your own exit routine, the function or command invokes the default routine. If you do write your own exit routine, you replace the routine that TSO/E provides with your own exit routine. The function or command then invokes your exit rather than the default exit TSO/E provides.

For other functions or commands, TSO/E does not provide a default exit routine. If you do not write your own exit routine, the function or command simply continues processing without invoking an exit routine. If you do write an exit routine, the function or command invokes your routine.

The individual descriptions of the exits in this document describe whether TSO/E provides a default exit routine for the particular exit.