II(RC, you are referring to the Link Pack Area (LPA). Regards, Richard Schuh
-----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, May 23, 2006 11:30 AM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: virtual memory In article <[EMAIL PROTECTED]>, Anne & Lynn Wheeler <[EMAIL PROTECTED]> wrote: [ snip ] >SVS evolved into MVS ... there was a separate address space for every >application. However, because of the heavy pointer passing paradigm, >the "MVS" kernel actually occupied 8mbytes of every application >16mbyte virtual address space. There was some additional hacks >required. There were some number of things called subsystems that were >part of most operational environments. They existed outside of the >kernel (in their own virtual address space) ... but in the MVT & SVS >worlds, other applications were in the habit of directly calling these >subsystem functions using pointer passing paradigm ... which required >the subsystems (which now were in separate address space) to directly >access the calling application's parameters in the application's >virtual address space. > >The initial solution was something called a "COMMON" segment, a (again >initially) 1mbyte area of every virtual address space where >applications could stuff parameter values that they needed to be >accessed by called subsystems, resident in other address spaces. Over >time, as customer installations added a large variety of subsystems, >it was unusual to find the COMMON segment taking up five megabytes. >While these were MVS systems, with a unique 16mbyte virtual address >space for every application, the kernel image was taking 8mbytes out >of every virtual address space, and with a five megabyte COMMON area, >that would leave a maximum of 3mbytes for application use (out of a >16mbyte virtual address space). (Just now working my way through this thread; great stuff .... ) Was there an acronym/initialism for this COMMON area? My memory of doing junior-level systems work on MVS systems is telling me that there was one, but not what. ? [ snip ] -- B. L. Massingill ObDisclaimer: I don't speak for my employers; they return the favor.
