User Exits › Exit Routine Programming Considerations › GCMSRCXT › Entry Environment

Entry Environment

Supervisor state, problem program key, AMODE 24, or AMODE 31. You must use this environment at entry and restore it upon return.

Register Usage at Entry

Common Parameter List

R1

Contains the address of the parameter list, in the following format:

+0

Contains the address of the parameter list for the GCMSRCXT routine. It is not used for initialization calls.

+4

Contains the communication word for the routine. During its initialization call, the routine may set the word contents. The contents are passed unchanged for all subsequent calls to this routine.

+8

Contains the fullword of flags used to pass status information to the routine. The first byte X'80' bit is set on for the initialization call.

+C

Contains the global communication word. The value of this word can be set by the MIMINIXT exit.

R13

Contains the address of the standard save area.

R14

Contains the return address for CA MIM for z/VM.

R15

Contains the entry point address for the GCMSRCXT routine. All other registers are undefined.

GCMSRCXT Parameter List (mapped by GCMWTOXP)

+0

Contains the address of the message selection table that you can use to change some of the routing data for this message. For a description, see Changing Routing Data through Exit Routines in this chapter.

+4

Contains the address of the message text table that you can use to change the text of this message. For a description, see Changing Message Text through Exit Routines in this chapter.

+8

Contains the one-byte length of the message text.

Return Code, Register 15

0

Indicates that CA MIC should accept this message (with any modifications you have made to it) and process it normally.

4

Indicates that CA MIC should reject this message.

Note: You must restore all registers (except 0, 1, and 15) upon return.