On Sun, 19 Jun 2016 15:32:07 -0400, Peter Relson wrote: > >The maximum region size is entertaining, but if you ever granted it, you >would probably cause the address space to fail. There isn't room for >x'7FF00000' bytes of user storage above the 16M line (and when you specify >a region size that big, it applies to the area above 16M), > Really? I had expected it would apply to both. What happens if a (legacy) program explicitly requests 24-bit storage? Does that mean that if I specify REGION=16385K, I can use that amount above the line *plus* whatever scraps are available below the line? (I understand I'll never get 16383K.)
On Fri, 17 Jun 2016 11:21:44 -0400, Jim Mulder wrote: >> >>For diagnostic purposes, then 4K page at 7FFFF000 is always >> >>left invalid in z/OS. >> > >> 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. > So it's fortuitous that the design meets both requirements. Or, the designers might have had similar motivaions in both cases. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
