IBM Mainframe Discussion List <[email protected]> wrote on 10/22/2006 12:19:36 PM:
> I've never understood why the CsvRentSp252 DIAG trap is necessary. What > is the rationale for ignoring the RENT attribute for unauthorized > programs? Authorized or not, a RENT program that modifies itself in an > unserialized way has a bug that could have serious ramifications for the > application. IMHO, by ignoring the RENT option for unauthorized > programs, the operating system does their owners a great disservice. The reason now is of course compatibility. For example, I have been told that there is a debugger program in the HLASM toolkit which runs unauthorized, and sets breakpoints by modifying the program being debugged. With CsvRentSp252, this debugger cannot set breakpoints in modules which have the RENT attribute. > Currently, there is a "refreshable" attribute that the binder > understands. That attribute is completely ignored by the operating > system. If the distinction between RENT and REFR were surfaced in > contents supervisor control blocks (there is a CDRENT flag bit in the > CDE but no CDREFR flag bit), then it's conceivable IBM could, without > too much effort, make REFR imply page protection. With that, we would > not need the CsvRentProtect DIAG trap and its associated exception > table! Our platform could do away with module overlays once and for all! > It would be tremendous RAS improvement! And as you know, that is on my list of things I would like to be doing if I had time to be doing things like that. Of course, doesn't hurt to submit a requirement. > > Will CSV and storage management ever allow load modules and data > > to occupy the same page? If so, a program might need to be > > protected with neutral zones on both ends. > > > Programs loaded into SP 252 are loaded into what are usually considered > to be "program-only" pages. CSV does a GETMAIN for the amount of space required by the module (unless you are using the undocumented CSVSP252ROUNDUP trap in DIAGxx). The remaining space in a page could be obtained from subpool 252 by another program for use as data. Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY ---------------------------------------------------------------------- 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
