I love transactional processing. I still remember the SHARE session where it was fully described and thinking that this will make life so much easier in the future. But I may fully retire before we can safely add it to our products without dual paths for another technique. In this case PLO was used for maintaining a doubly-linked list. The alternative, which we use in other situations, is a CS or CDS lock, which means code to spin a while, go idle (in case of a uni or CICS QR TCB), clean up in case of an abend, timeout, region termination, messages to tell us and operators what's happening, and dumps of our control blocks.
I requested the PLO info because a programmer came across the instruction while debugging a problem and had the PoOp open to the first page of the PLO description and I am leaving on vacation. And, truth be told, I'd have to reread the PoOp again to describe just what I was thinking 10-12 years ago when I added the instruction after a problem occurred where we'd previously assumed the probability of two processes concurrently maintaining a doubly-linked list were infinitesimal. It turns out they were very small but finite. Perhaps I'll start adding dual path transactional processes just so it's documented that there is an alternative. Gary Weinhold Senior Application Architect DATAKINETICS | Data Performance & Optimization Phone: +1.613.523.5500 x216<tel:+1.613.523.5500%20x216> Email: weinh...@dkl.com<mailto:weinh...@dkl.com> [http://www.dkl.com/wp-content/uploads/2015/07/dkl_logo.png]<http://www.dkl.com/> Visit us online at www.DKL.com<http://www.dkl.com/> [http://www.dkl.com/wp-content/uploads/2015/08/banner.png]<http://www.dkl.com/mailsig> E-mail Notification: The information contained in this email and any attachments is confidential and may be subject to copyright or other intellectual property protection. If you are not the intended recipient, you are not authorized to use or disclose this information, and we request that you notify us by reply mail or telephone and delete the original message from your mail system. __________ On 2017-08-11 09:31, Blaicher, Christopher Y. wrote: PLO is an expensive instruction. It can do a little or a lot. There are about 10 pages in the POP to describe it. However, until transactional processing is supported in all environments, ISV's, who never know what environment they are running under, need to keep using the PLO instruction. OK, Peter, we could dual path it, but who likes to maintain dual paths? Chris Blaicher Technical Architect Mainframe Development P: 201-930-8234 | M: 512-627-3803 E: cblaic...@syncsort.com<mailto:cblaic...@syncsort.com> Syncsort Incorporated 2 Blue Hill Plaza #1563 Pearl River, NY 10965 www.syncsort.com<http://www.syncsort.com> Data quality leader Trillium Software is now a part of Syncsort. -----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of John McKown Sent: Friday, August 11, 2017 9:10 AM To: MVS List Server 2 <ASSEMBLER-LIST@LISTSERV.UGA.EDU><mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU> Subject: Re: PLO <subject change: was Just Testing - It got very quiet> On Fri, Aug 11, 2017 at 6:23 AM, Peter Relson <rel...@us.ibm.com><mailto:rel...@us.ibm.com> wrote: <snip> does anyone know of good write-ups/presentations of PLO and its capabilities and uses for an assembler programmer who knows how to use CS and CDS. </snip> My hope is that, going forward once you have a machine that supports it and, for those who care about z/OS under z/VM, once/if it is supported for z/OS running under z/VM, no one ever uses PLO again but instead uses transactional execution, particularly TBEGINC for the simpler cases. Peter Relson z/OS Core Technology Design Now, that is a very interesting statement. -- If you look around the poker table & don't see an obvious sucker, it's you. Maranatha! <>< John McKown
