That's always been an issue since virtual storage limits far outpace the ability of real and auxiliary storage to back all potential pages. One 64 bit address space could kill a system. Does ANYONE have 16exabytes of aux storage? No! When we first went to ESA one slick application programmer decided to try to issue a GETMAIN for all storage above the line and then access each page. He crashed one of our systems. This hole has not been closed and, in fact, is even bigger now with 64 bit storage.
-----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Martin Packer Sent: Monday, April 25, 2011 4:41 PM To: [email protected] Subject: Re: MEMLIMIT Parameter Question Before people (continue to) post their MEMLIMIT values don't we think there's a potential Denial Of Service issue here? If a program were to touch every page up to gazillion whatobytes there'd be a problem. MEMLIMIT is one of the mechanisms that limits this potential. IEFUSI is another. The same is probably true of HVSHARE and HVCOMMON, while we're at it. Cheers, Martin Martin Packer, Mainframe Performance Consultant, zChampion Worldwide Banking Center of Excellence, IBM +44-7802-245-584 email: [email protected] Twitter / Facebook IDs: MartinPacker Blog: https://www.ibm.com/developerworks/mydeveloperworks/blogs/MartinPacker Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU ---------------------------------------------------------------------- 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 This e-mail may contain confidential or privileged information. If you think you have received this e-mail in error, please advise the sender by reply e-mail and then delete this e-mail immediately. Thank you. Aetna ---------------------------------------------------------------------- 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
