On Fri, 17 Jun 2016 11:21:44 -0400, Jim Mulder <[email protected]> wrote:
>> >>For diagnostic purposes, then 4K page at 7FFFF000 is always >> >>left invalid in z/OS. >> > >> >That makes the highest numbered, accessible byte to be at address >x'7FFFEFFF' >> > >> That might be due to a requirement of ANSI C that there always be an >address >> algebraically greater than that of any accessible object, for loop >termination >> conditions. > > Not likely. It has been that way since the first release of MVS/XA, >circa 1982. That was a time when MVS still ruled with arrogance, and it >would takes some doses of marketplace reality changes a few years later >before >MVS became interested in accommodating C and Unix. In any case, "ANSI" C didn't exist until (I think) 1989, though the standardization effort began in 1983. So the technique is certainly older than ANSI C, and not related to it. -- Walt ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
