gtpi1m09System Installation Support Reference

Exit Points

Exit points are predefined locations in TPF system processing from which user-unique processing code can be invoked. This user-unique code (called user exit, user exit routine, and user processing) will then execute as an extension of a TPF system function.

Exit point status is not carried across an IPL. The ZSTIM command can be used during restart, cycle-up, or cycle-down to automatically activate or deactivate exit points.

A dynamic control program exit point is one that can be activated or deactivated by an online macro (UXCMC) issued from a program. A nondynamic control program exit point does not change. It is active or inactive. You cannot change it without reinitializing the system.

Changing Dynamic Exit Points to Nondynamic

Note:
Dynamic overlay exits (exits that change the control program code with exception code) cannot be changed to nondynamic.

To change a dynamic exit point to a nondynamic exit point, you must do the following:

  1. Change the corresponding entry in the &ATT (attribute) table of the DCTUCL macro to "UCLXPA" (nondynamic and active).
  2. Assemble CCUEXT and CCNUCL, and link-edit the control program.
  3. Make sure that you have removed all UXCMC macro calls treating this user exit as dynamic.

Changing Nondynamic Exit Points to Dynamic

Changing nondynamic exit points to dynamic exit points requires modification of control program code (at the exit point) and any related initialization code. Therefore, it is not recommended.

Associating an Exit Point with a Function

You may want to associate specific exit points with a function (for example, test tools, accounting, data collection, and others) so the function can be activated or deactivated using a command. If you do, make sure that the exit point can be deactivated and is not being used by another function.

Multiple Functions in User Exits

You may need to implement more than one function in a user exit. If you do, macros are provided that allow you to define and control multiple functions residing in a single dynamic or nondynamic user exit.