Answer: Not totally It is true that all current machines support page 0 in a data space, and for them the "normal" origin returned would be 0. That is not a guarantee that all future machines would have such support, but I find it hard to believe any would not.
However, we have found it highly desirable to avoid using page 0 of the data space, in order to avoid ZAD events (which in turn make it more difficult to spot ZAD errors). The best way to do that is to use HideZero=YES on DSPSERV CREATE (available since z/OS 2.1). And when that is done, the origin returned is x'1000'. With HideZero=YES, any reference to the first 4K will fail, so that you don't even need ZAD to find erroneous references. For us, best practice is to create a 2G data space (not 2G-4K), treat RC=0 and RC=4 as OK, use HideZero=YES, and use an Origin of x'1000'. So you never really need to use the Origin keyword if you simply start at x'1000'. There is a non-zero but miniscule risk if you assume that it is OK to use an origin of 0. Peter Relson z/OS Core Technology Design ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
