User Exits › Common Exit Interface: MIMCMDXT › Coding Rules

Coding Rules

Follow these rules when coding the MIMCMDXT routine:

• Preserve all registers except registers 0, 1, and 15.
• Review all code that you define in this routine to prevent ABENDs from occurring. This product may try to recover from ABENDSs but can terminate when it experiences repeated ABENDs.
• Do not use these macros
  • GCS OPEN
  • CLOSE
  • LOAD
  • LINK
  • BLDL

  Or any other GCS macro that implicitly or explicitly calls the WAIT supervisor.

• Do not use the STIMER or TTIMER macros.
• Ensure that you interpret the command name properly when intercepting a command with this routine. Command names are converted to the new name (and parameters). Therefore, base your comparisons on the true command name rather than any alias.
• If you want to alter the command text, do so at offset +4 and not at offset +0.
• Provide a save area of at least 72 fullwords if you want to issue messages from this routine. For the mandatory code for this subroutine, see the example in Issuing Messages from MIMCMDXT in this chapter. Also, do not change registers 10 or 11 if you use this subroutine.
• Use the EXIT parameter on the SETOPTION command to identify the appropriate load module for the MIMCMDXT routine. For example, specify SETOPTION EXIT=MIMCMDXT when the module name is MIMCMDXT. If you use a different module name, specify EXIT=MIMCMDXT and specify the module name on the LOAD parameter. For example, to use the load module UEXIT1 for the MIMCMDXT routine, specify the command SETOPTION EXIT=MIMCMDXT LOAD=UEXIT1.
• To assemble an exit, use High-Level Assembler.

Assemble and link edit the completed routine as an authorized program into a load library and include the load library on the GLOBAL LOADLIB command in the PROFILE GCS for the MIMGR ID. Use the module name that you provided during the assemble and link edit to activate the exit through the SETOPTION EXIT command.

The sample file named MIMCMDXT ASSEMBLE on your distribution tape contains a sample exit that you can modify. A LINKEXIT EXEC is provided on the tape to link the sample routine into a load library called MIMEXITS LOADLIB.

For more information on the SETOPTION command, see the CA MIM Statement and Command Reference Guide.