(sorry for being late joining in) IMO, no one would ever use SYNCH(X) unless they had a functional reason to do it. If you have the address of something, you would typically simply BASR to it (or something similar).
One functional reason is for authority-decreasing. I believe that it can be correctly stated that SYNCH(X) is the only authority-decreasing mechanism truly supported by z/OS. Note that I intentional wrote "z/OS". Authority-decreasing can be accomplished by PC too (and there is nothing that the operating system can do to stop you from doing it) but I suspect that there could be potential system integrity holes in doing so). RTM uses SYNCH(X) to move from supervisor state to the state needed by an ESTAE-type recovery routine.. Peter Relson z/OS Core Technology Design ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html