User Exits › Exit Routine Programming Considerations › MIMCMDXT Exit

MIMCMDXT Exit

You can use the optional MIMCMDXT exit routine to prevent certain CA MIM commands from being issued on the local system or across systems. You can also increase the command authority level associated with a console or TSO user ID so that operators or TSO users can issue CA MIM commands that they could not issue otherwise.

You cannot use this routine to prevent z/OS or JES commands from being issued on a local system or to increase the command authority level needed to issue z/OS or JES commands. You can change the length and contents of the text of a command with the MIMCMDXT routine.

CA MIM invokes this routine whenever it issues a command on the local system and whenever a cross-system command is issued from the local system.

Follow these rules when coding the MIMCMDXT routine:

• Preserve all registers except registers 0, 1, and 15.
• Review all code you define in this routine to prevent abends from occurring. CA MIM may try to recover from abends, but can terminate if it experiences repeated abends.
• Do not use the z/OS OPEN, CLOSE, LOAD, LINK, or BLDL macros, the TSO facilities, or any other z/OS facility that implicitly or explicitly calls the WAIT supervisor.
• Do not use the STIMER or TTIMER macros.
• Make sure that the routine uses the appropriate command authority level for each situation.
• If you use the CA MIC LINK command to change the authority level for a TSO user or console, then CA MIM uses the authority level assigned by the LINK command for cross-system commands. Otherwise, TSO users are assigned informational command authority (X'0000'), and the command authority level for an MCS console is established in the control block for that console.
• TSO users and consoles need informational command authority to issue CA MIM display-type commands. They need system control command authority (that is, X'80') to issue other CA MIM commands.
• Make sure that you interpret the command name properly when intercepting a command with this routine.
• Cross-system commands are stripped of their command characters by the time the routine intercepts them. Also, command aliases are converted to the new command name (and parameters). Therefore, base your comparisons on the true command rather than on any aliases you have defined for that command.
• If you want to alter the text of a command, then 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. Mandatory code for this subroutine is shown in the example included 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, then 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).

Assemble and link-edit the completed routine as an authorized program with the module name you specify on the SETOPTION command.

Link-edit the routine into the authorized load library for CA MIM.

The sample member named ASMEXIT in the CAI.CBTDJCL data set contains JCL that you can use to assemble and link-edit this routine.

Note: For more information, see the Statement and Command Reference Guide.