On Mon, 21 Apr 2014 11:44:01 -0500, Paul Gilmartin <[email protected]> wrote:
>On Mon, 21 Apr 2014 07:01:50 -0500, Tom Marchant wrote: > >>On Fri, 18 Apr 2014 14:07:29 -0500, Paul Gilmartin wrote: >> >>>Are there separate pools of real storage for above the bar and below the bar? >> >>Pools? No. Pools are a software concept. >> >>Real storage with real addresses < 2 GiB are below the bar. >>Real storage with real addresses > 2 GiB are above the bar. >> >ITYM ">= 2 GiB" > >But what do you call real storage with a real address = 3 GiB or >thereabouts? I understand that for historic reasons, pertaining >only to z/OS, not other OSes, 2 GiB <= virtual address < 4GiB >is prohibited, and GETMAIN (STORAGE?) for even 64-bit >addressable storage will not return storage in that area. But >why? What harm would befall if it did? > Search the archives. That hasn't been true for quite some time now. 64-bit Java used it first, but it isn't restricted to Java. I don't know if anything else is using it at this point. The harm / fear was misinterpreting 31-bit addresses as 64-bit addresses in 64-bit programs processing 32-bit address words that had the high order bit set on either unintentionally (leftover garbage) or intentionally for something meaningful. Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS ITIL v3 Foundation Certified mailto:[email protected] Mark's MVS Utilities: http://www.mzelden.com/mvsutil.html Systems Programming expert at http://search390.techtarget.com/ateExperts/ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
