On 6/30/2012 7:57 AM, Edward Jaffe wrote:
For example, if a z/OS system is now capable of running 1000 more address spaces than it could twenty years ago, that means 384,000 additional bytes of fixed, common storage below 16MB is required just to hold the ASCBs (address space control blocks -- 384 bytes each)! There are other fixed, common storage control blocks needed as well. And 24-bit common storage, whether fixed or not, reduces the amount of 24-bit virtual private area available.
Lol! In reading back my post as it was echoed to me, I see I failed to directly state the most important point. :-[ While there is one shrinking virtual 24-bit area per address space, there is ONLY ONE 24-bit real storage area shared by the ENTIRE SYSTEM! So, not only does growth of fixed, common 24-bit storage 'eat' into the total that is available, but private 24-bit addresses when they are fixed (such as during an I/O) are competing for an ever-shrinking pool of 4K frames in that singular system-wide area. 24-bit I/O. Don't do it! -- Edward E Jaffe Phoenix Software International, Inc 831 Parkview Drive North El Segundo, CA 90245 310-338-0400 x318 [email protected] http://www.phoenixsoftware.com/
