gtps4m1q | System Generation |
In the past, many users of TPF made modifications to the control program in order to support their unique processing needs (for example, accounting, test tools, and so on). These modifications then had to be reinvestigated and reimplemented with each migration to a new release of TPF.
In order to alleviate this problem, a set of predefined user exit points has been provided within the TPF control program. These user exit points, when activated, will cause the TPF control program to pass control to user-supplied routines, which may then perform their processing as an extension of the control program.
In order to implement this function, the user must update the source code in copy member CUSR (control program CSECT CCUEXT), assemble CCUEXT, and link-edit the control program to include the updated CCUEXT CSECT.
The user-unique code is thus isolated from the released TPF control program and need only be changed if the exit point interface has changed (for architectural design reasons) when migrating from one release of TPF to another.
The source code for copy member CUSR (as released) contains commentary only, describing the exit point interfaces.
Also, the user will have to provide an E-type program to control the activation/deactivation of the defined exit points.
See TPF System Installation Support Reference for more information about user exits.