John, IIRC the addition of HVCOMMON is due to customer requests for it - for some maybe the setup required and usage for shared memobjs must have been too difficult to implement.
I would also guess that using any non-primary mode and a special ALET is not going to be very popular as there are *many* services that cannot be called in AR mode - and the last time I looked the SAC instruction was slower than a snail with a limp - so you do not want to be issuing too many of those fellas to keep switching in and out of primary. Rob Scott Developer Rocket Software 275 Grove Street * Newton, MA 02466-2272 * USA Tel: +1.617.614.2305 Email: rsc...@rs.com Web: www.rocketsoftware.com -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of McKown, John Sent: 19 May 2009 19:43 To: IBM-MAIN@bama.ua.edu Subject: common area [E]CSA question / idea / idiocy I'm reading the paper about IBM's plans for the 64-bit common (HVCOMMON?). And I'm really beginning to wonder about something. What this will do is create another block of storage which is mapped into every address space. I am curious why IBM has not considered using AR mode and a SCOPE=GLOBAL dataspace set up and IPL time, anchored to *MASTER* for some of these data areas. At present, from my reading, there are three ALETs with special values. ALET==0 is for the Primary address space. ALET==1 is for the Secondary address space. And ALET==2 is for the Home address space. How about ALET==3 being for a "common GLOBAL data space"? Is there some reason for products such as DB2, IMS, CICS, MQ, ..., requiring that the "common" area be addressable in "primary" mode at all times? Mainly curious. Is AR mode that much more difficult / restrictive than AMODE(64)? John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * (817)-961-6183 cell john.mck...@healthmarkets.com * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
