On Tue, 30 Nov 2010 23:09:00 -0600, Chris Craddock wrote: > >However, if you were imagining you would be executing code that was above >4GiB, then forget it. z/OS doesn't support it at all. Even if you >could somehow conspire to get some code into storage above the bar, you >would not (in general) be able to execute it successfully because none of >the major control blocks that manage dispatching work can support saving a >full extended PSW, so while you might "get away with it" for a few >instructions, the moment you took an interrupt you'd be toast. Hence the >putative requirement to run disabled. For the purposes of this discussion >you may assume that's just a bonehead idea. > As you've made it pretty clear, that's merely a software limitation. Other operating systems such as z/VM and Linux for z run code -- how to say it? "Above the bar" doesn't fit, since they have no bar. Well, up there, anyway. And I understand that under z/OS, Java has a special Papal dispensation to use storage within the bar, I don't know whether for code or only for data.
As more code, and perhaps even sharable data get loaded into LPA, will a 2GB virtual storage constraint soon become onerous? I understand content supervision will nowadays load CSECTs above the bar, and correctly relocate 64-bit ADCONs, but they'd better be data only; no code. -- gil ---------------------------------------------------------------------- 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
