Peter, Sorry for my re-visit to this thread cause today I read something about FIXED and DREF virtual storage area and feel that something should be added.
For FIXED area, it's no longer true: when you GETMAIN, all pages will be backed up by real frames because FIXED area is supposed to serve disabled user. And in my opinion, that's why DREF is superior to FIXED: it's backed up by real frames only when you access it for the first time (like pageable area). And MVS has special facility to make it suitable for disabled user. Of course like FIXED area, after first reference DREF pages will be fixed there unless released or swapped out (for private area). I know the above is not true if you have expanded storage installed: these DREF pages can be copied to expanded storage. But, does z/os still use expanded storage? I think no. On 10/5/07, Hunkeler Peter (KIUK 3) <[EMAIL PROTECTED]> wrote: > >>After a successful GETMAIN request, I will get a virtual storage area > to > >Is that area supported by either real storage or auxiliary storage as > >soon as the GETMAIN completes? > > This is where PIC 10/11 enter the scene: You got your virtual storage > but > it is not yet associated with any real storage. When your code > references > any address in that range for the first time, DAT will fail to translate > the virtual address and will signal a PIC 10 or 11 (as explained in my > previous post). z/OS gets control, validates your request using the VSM > control blocks, and if it is valid (i.e. your trying to access GETMAINed > storage), a real storage frame will be assigned, your instruction is > repeated and will succeed. (No auxiliary storage involved so far.) -- Best Regards, Johnny Luo ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
