A debugging investigator made wary by previous encounters with Dr. Murphy should assume that any hypothetically possible situation will occur, and especially if the consequences are the most severe. So the TCB occasionally is being suspended because the local lock is not available.
I have seen a cross-memory POST take as much as one half of a second to complete, during which time the unit of work doing the POST is in a disabled CPU spin loop which is, at some level of viewpoint, indistinguishable from a WAIT. Bill Fairchild Software Developer Rocket Software 275 Grove Street * Newton, MA 02466-2272 * USA Tel: +1.617.614.4503 * Mobile: +1.508.341.1715 Email: [email protected] Web: www.rocketsoftware.com -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Wayne Driscoll Sent: Wednesday, December 02, 2009 10:31 AM To: [email protected] Subject: Re: question on STORAGE function - TCB may become non-dispatchable? A PC-cp doesn't have any sort of implicit wait, so I don't see what they are referring to in that sense. Both GETMAIN (a type one SVC) and the STORAGE PC routine will, at some point have to get the local lock, which will cause a suspension if and only if the lock is unavailable. =============================================== Wayne Driscoll OMEGAMON DB2 L3 Support/Development wdrisco(AT)us.ibm.com =============================================== From: "McKown, John" <[email protected]> To: [email protected] Date: 12/02/2009 10:11 AM Subject: question on STORAGE function - TCB may become non-dispatchable? Sent by: IBM Mainframe Discussion List <[email protected]> There is an ongoing discussion on the CICS-L list about doing a STORAGE macro or GETMAIN/FREEMAIN. Some are saying that these functions can result in a "wait" for the CICS QR TCB (the TCB under which most of the CICS transactions are run). The discussion has now become that the STORAGE macro issues a PC, which does an implicit "wait". My opinion has been that a normal STORAGE function does not do a ss-PC or cause the TCB to wait. It may take some CPU and cause response time problems, but the z/OS TCB does not go into a WAIT or SUSPEND state (non-dispatchable). Anybody have a definate response as to whether a STORAGE function can cause the TCB to become z/OS non-dispatchable. I agree that it is not a good idea to do this in CICS. 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 [email protected] * www.HealthMarkets.com ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] 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 [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
