Why was the default LINKAGE=SYSTEM for STORAGE OBTAIN? Because it was a new interface, and needs to handle environments that are not suitable for SVC.
STORAGE OBTAIN,LINKAGE=SYSTEM might be slower than SVC-entry GETMAIN (AKA STORAGE LINKAGE=SVC) because it does more. For example, it accepts XM invocation, it accepts ALET-identified target space. I believe in most cases the "target module" for STORAGE OBTAIN,LINKAGE=SYSTEM gets control faster than the "target module" for GETMAIN. The SVC interrupt handler isn't "free" and the instructions executed in that path might take comparable cycles to the PC. I'd not be surprised if PC-entry is faster than SVC-entry for obtaining common storage if there is any likelihood of LOCAL lock contention. PC-entry would not try to get the LOCAL lock; SVC-entry is a type 1 SVC and always gets (and holds to completion) the LOCAL lock. Peter Relson z/OS Core Technology Design ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
