z/OS User Exits › Customizing and Installing z/OS User Exits

Customizing and Installing z/OS User Exits

The easiest way to customize a user exit is to copy and modify the code supplied by CA. Always read the source code of the exit as well as the additional information included in comment lines. These lines are placed where you would need to enter code to customize the exit for a specific need or function.

The steps involved in customizing any user exit are as follows:

• Copy the default exit from the CA Gen CEHBSAMP library to one of your libraries.
• Add the desired new code to the copied exit. Do not change the 'Program ID' (entry point) or argument list passed to the exit.

Most user exits are called with RUNTIME-PARM1 and RUNTIME-PARM2 as the first two parameters. Under IMS, the RUNTIME-PARM parameters are mapped to the IO-PCB and ALT-IOPCB, respectively. If an exit is modified to use the IO-PCB and/or the ALT-IOPCB, remember to remove the corresponding RUNTIME-PARM from the LINKAGE SECTION and the PROCEDURE DIVISION USING statement.

Under CICS, the RUNTIME-PARM parameters are mapped to the CICS EXEC Interface Block (EIB) and the COMMAREA, respectively. If an exit is modified to use DFHEIBLK and/or DFHCOMMAREA remember to remove the corresponding RUNTIME-PARM from the LINKAGE SECTION and the PROCEDURE DIVISION USING statement. In addition, remove these parameters if the modified exit is processed by the CICS translator as the CICS translator automatically includes a reference to DFHEIBLK and DFHCOMMAREA.

Information about the presence and use of RUNTIME-PARM parameters is included in the CEHBSAMP member for each exit and is covered in this chapter if relevant.

The remaining parameters are unique to each exit and should not be modified.

Ensure the new runtime modules are placed in the proper data sets as follows:

• CICS – in the CICS DFHRPL concatenation and is New Copied into CICS.
• IMS – in the steplib concatenation.

As delivered, the Exits contain no SQL and no DBRMs. If a User Exit calls another routine that does database access, you need to add that routine's DBRM to the installation control file so the routine can be found. The best way to accomplish this is to modify the Installation CLIST, TICINSTX, so that it adds the DBRM to the DBRM list.

The following table identifies the z/OS JCL procedures used to compile and bind each of the z/OS Server Manager User Exits into their respective DLLs. These JCL procedures are located in the CA Gen CEHBSAMP library.

Each DLL may contain other user exits that are not directly in support of the processing of a z/OS Distributed Processing Server (DPS). Additionally, the list of z/OS user exits may also be used to support z/OS blockmode and batch operation.

Details of the preceding JCL procedures follow. Each one is described in a separate section.