User Exits › Exit Routine Programming Considerations › XCMCMDXT Exit › Register Usage at Entry

Register Usage at Entry

Common Parameter List

R1

Contains the address of the parameter list for the exit. The UXPARM member of the CAI.CBTDMAC data set contains a DSECT mapping for this parameter list. It has the following format:

+0

Fullword containing the address of the exit-specific parameter list for the XCMCMDXT exit routine. The exit-specific parameter list is mapped by the XCMCMDXP mapping macro that is contained in the CAI.CBTDMAC data set.

Note: This is not used for exit initialization calls.

+4

Fullword containing the communication word of the XCMCMDXT exit routine. The content of this word may be set by the routine during its initialization call and is passed unchanged for all subsequent calls. This word is set to zero when the routine gets control over the first initialization call. If CA MIM is restarted, the value set during the first initialization call is passed during any subsequent initialization calls, unless the z/OS system has been IPLed.

+8

Fullword containing flags used to pass status information to the exit routine. The high order bit of the first byte is set on (X'80') for the initialization call.

+C

Fullword containing the global communication word, set by the MIMINIXT exit routine.

R13

Contains the address of a standard 18-word register save area.

R14

Contains the return address for CA MIM.

R15

Contains the entry point address for the XCMCMDXT exit routine

All other register contents are undefined upon entry to the XCMCMDXT exit routine.

XCMCMDXT Exit-specific Parameter List

Offset +0 in the common exit parameter list (mapped by UXPARM) points to the XCMCMDXT exit routine-specific parameter list. See member XCMCMDXP in the CAI.CBTDMAC data set for a mapping macro for this parameter list. You can set various flags and values in the XCMCMDXP parameter list to influence conflict actions for the requester involved in the resource conflict.