-----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Michael Knigge Sent: Friday, October 09, 2009 3:34 AM To: IBM-MAIN@bama.ua.edu Subject: Does a DD-Statement "waste memory" after dealloc?
All, I currently try to find a obscure memory leak in one of our applications. After some days our appl occupies ~17.000 pages of real memory (needs just ~1.500 after startup). As we track all malloc(), calloc(), realloc() and free() function calls, I can say that there is no obvious memory leak.... Now... after I've looked at the JESYSMSG I've noticed that we've done approx 17.000 DYNALLOCs, everyone with a different DD-Name (we let the z/OS generate a unique one, like "SYS00001", "SYS00002", "SYS00003" and so on)..... to be clear: *NOT* ~17.000 at the same time. mostly only one at the same time... Of couse, we deallocate them after we've finished using the DD-Name, but I wonder that even after a DEALLOC (with SVC99) there is some space still occupied.... Why? Because of performance? Because of some kind of control block that can only grow but not shrink? <SNIPPAGE> We have found two things in this area. Both are involved in LSQA. One has to do with ACEE (and associated storage) and the other is the dynamic allocation. We also used DYNAMNBR on EXEC statements (see JCL REF). You may find that this alleviates some of the storage creep. Regards, Steve Thompson -- Opinions expressed by this poster may not reflect those of poster's employer -- ---------------------------------------------------------------------- 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
