I am not opposed to large address spaces but I need to make sure that my systems stay up. Until someone comes up with a way to back large address spaces then we are in a dangerous situation. It may be 'virtual', but if anyone tries to use it there had better be SOMETHING backing it up! Coding IEFUSI to limit its use is defeating the purpose of having large address spaces in the first place. I remember losing a system when we went to 31 bit addressing because a smart application programmer wrote a program that did a GETMAIN for all available storage and then referenced every page, which killed our paging subsystem. 64 and 128 bit addressing only exacerbate this problem. You may have 64bit addressing, but you only really have the amount of real storage on your system plus the amount of paging space available. Try to use any more and its CRASH.
Jon L. Veilleux [EMAIL PROTECTED] (860) 636-2683 -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of john gilmore Sent: Tuesday, July 18, 2006 10:40 AM To: [email protected] Subject: Re: 64-bits is a really big number! Chris Craddock writes: | | . . . I am glad that the wizards have made it all work out, but in | terms of functional needs, | 64-bit addressing is overkill on a cosmic scale. | Let us hope so. Computing---informatique, informatica, whatever---is a fairly new discipline; but one red thread that runs through its brief history is that nothing is ever big enough for long. External names at most eight characters in length, DDNAME values at most 44 characters in length, varying (halfword current-length prefixed) strings at most 32767 bytes in length, fullword values not larger than 2147483647, etc., etc., have all proved to be too small. Moreover, address spaces first 24 and then 31 mibibytes in size have quickly proved to be too small, not for every application but for some crucial ones. The moral of this anecdotage is that notionally "reasonable" maxima have in our history always been outgrown much too soon. Another obvious point to make is that this storage is virtual not real storage. All of it need not be backed up, and what is backed up need not even be connected (contiguous); and still another perhaps not quite so obvious one is that when four-byte addresses are inadequate, there are compelling architectural reasons for moving to eight- and not five-, six-. or seven-bye ones. Those of you who have not used the 'new' 64-bit facilities need to learn to do so. Moreover, time spent mastering them will have been used to better advantage than time spent dismissing them as unrealistically sized. John Gilmore Ashland, MA 01721-1817 USA _________________________________________________________________ On the road to retirement? Check out MSN Life Events for advice on how to get there! http://lifeevents.msn.com/category.aspx?cid=Retirement ---------------------------------------------------------------------- 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
