Johnny, This is an extremely complicated process, based on a number of factors, many of which your program has no control. However, your guess is usually correct, in that if the page returned has never been allocated to your program, then no real or aux storage will be allocated. On the first reference, the hardware will recognize an 0C4, which will be handled by the OS on your behalf and RSM and ASM will get involved to locate a page for you. Your program will NOT see this 0C4, unless in the highly unlikely situation that there is no real storage available.
Wayne Driscoll Product Developer JME Software LLC NOTE: All opinions are strictly my own. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Johnny Luo Sent: Wednesday, October 03, 2007 6:57 AM To: [email protected] Subject: GETMAIN/FREEMAIN and virtual storage backing up Hello, GROUP I spent the whole day reviewing my understanding about the concept of virtual storage and found something I cannot figure out. I hope experts here can give me some hints. Maybe I should start from GETMAIN. I have used GETMAIN/FREEMAIN for some time in my programming exercises and one question has remained on my mind from the first day I knew these services: After a successful GETMAIN request, I will get a virtual storage area to use. Is that area supported by either real storage or auxiliary storage as soon as the GETMAIN completes? My guess is: it depends and it's very possible that it is not. ---------------------------------------------------------------------- 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
