For Tape Management system that has not been tailored to the Server (or if only Save commands like SAVLIB are used without TMS), a facility (Breaker or Break Message Handler) is provided to automatically mount a specific or scratch tape into a tape drive, so that the backup or restore operation can go on.
“Break Message Handler” specifically handles CPA0488 with the response “G”:
CPA4088 Load Next Tape volume on device &4 (C G) – LMS/400 Action “Load Scratch Volume on device &4” and LMS/400 Reply “G” Depending on the VOL keyword, a specific volume or a scratch volume is loaded.
When issuing a SAVxxx or RSTxxx command, the VOL parameter should be specified to load a specific volume (and VOL=*MOUNTED can be mentioned to load a scratch volume).
Specifying the specific volume in the command would ensure that the specific volume (and not any scratch volume) is loaded.
But if you definitely do not want the message to be handled automatically, you can deactivate the Break message handler.
DSPDEVD TAP01 can be used to get the tape device description, which also shows if it is with or without Break Message Handler. It will show message queue as TAP01 in ATLDTALIBS if it is with Break Message Handler .
If exists, then Break Message Handler can be deactivated manually using “RELDEVMSGQ DEV(TAPXX)”