On 6/16/2016 3:57 PM, Jim Mulder wrote:
For diagnostic purposes, then 4K page at 7FFFF000 is always
left invalid in z/OS.
And what a valuable design decision that was!
We routinely load base registers and "uninitialized" pointers to
7FFFF000 (or sometimes 7FFFFBAD) rather than zero.
Even in 64-bit mode you can leverage 00000000_7FFFF000, but that's only
a 4K page. It could be helpful to have similar treatment for the 2G page
at FFFFFFFF_80000000 as well.
--
Edward E Jaffe
Phoenix Software International, Inc
831 Parkview Drive North
El Segundo, CA 90245
http://www.phoenixsoftware.com/
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