Design overview

The task-related user exit interface is comparable with the EXEC interface. When an application program requests the services of a non-CICS® resource manager, it does so by a module called the task-related user exit. The exit receives arguments from the application program, and passes them on to the resource manager in a suitable form.

The advantage of this method is that if the resource manager is changed, the application program that invokes the resource manager should not need to be changed too.

The exit is part of the resource manager programs. The name of the exit, or the name of the entry to the exit, is specified by the resource manager, and each application program that invokes the resource manager must be link-edited with an application program stub that refers to that name.

The exit is enabled and disabled by using the user exit manager (DFHUEM). For enabling, the resource manager can specify the size of a task-related work area that it requires.

The exit, when enabled and then driven, receives arguments in the form specified by the DFHUEXIT TYPE=RM parameter list (see Task-related user exit programs or the manual). Register 1 points to this parameter list. Register 13 points to the address of a save area, rather than the address of the CSA. The save area is 18 words long, with registers 14 through 12 stored in the fourth word onward.

Responses to the request are indicated by values placed in register 15, and also by means that are specific to the architecture of the application interface, for example, by moving data into storage areas passed by the call, or into the caller's register 15.