On 7/5/2011 1:57 PM, Steve Comstock wrote:
WOW! That's a big deal. Is this documented somewhere public? Or is this NDA? Do you what the "certain restrictions" are? Can you tell us? Can you tell us how it's done?
The Feb 15, 2011 announcement preview is the only public information I'm aware of. It tells you a lot if you know how to translate the 'announcementese'. It's been out there four months which proves (I guess) that nobody reads these announcement previews. Many thanks to Jim Mulder for bringing this to light on IBM-MAIN!
The previewed enhancement allows 'applications' that need 'virtual storage constraint relief' (i.e., ordinary, enabled, DAT-ON code) to have some 'programs running in 64-bit storage'. From that we can infer that the operating system can now save status over an interrupt for code located above the bar.I agree that is a 'big deal'!
The part where IBM talks about this enhancement providing VSCR to applications that 'imbed code in data areas' seems to suggest that applications might have to manually copy eligible code into data areas above the bar. If so, that seems like a pretty big 'restriction' to me.
Other possible 'restrictions' immediately come to mind as well. For example, there are hundreds of callable z/OS services. I imagine the process of inspecting, updating, testing and documenting required to make them all work for callers executing above the bar will take years. Enablement and/or approval of each service will likely need to be individually justified for expenditure of necessary development, test and tech-writing resources. In z/OS 1.13, probably only a handful (or possibly none!) of the z/OS services will have been enabled/approved for use by such code.
Saving status over an interrupt is indeed a 'big deal', but only the tip of the iceberg...
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