My guess as to why the OC is used is because fork will use a Copy on Write (COW) protocol for the new address space. They run through the JPA and do an OC on each page in order to get the modules copied over. This is probably since they can't just re-load all the modules, since source library info isn't saved. The sad part of this logic, is that if the program does a FORK->EXEC (which is pretty standard), the EXEC will get rid of most of the loaded modules. Garth Godfrey or Erin Farr would have the definitive answer to this.
Wayne Driscoll Product Developer NOTE: All opinions are strictly my own. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Edward Jaffe Sent: Thursday, June 12, 2008 1:14 PM To: IBM-MAIN@BAMA.UA.EDU Subject: APAR OA25468 We just opened APAR OA25468 against z/OS UNIX. If you run with REFRPROT in PROGxx, you can be hit by this. IIUC, z/OS UNIX fork processing uses the OC instruction, while in PSW key zero, to WRITE on EVERY PAGE of EVERY MODULE in the private area of the address space! (Who designed this???!) That's the scary part. Now page down to the bottom to see the funny part -- especially suggestion #2. |LOCAL FIX: |1. Refrain from using the PROGxx REFRPROT parm. if possible. | |2. Re-link the affected module so it is not using the | REFRESHABLE attribute. Yeah. Sure. How many modules in typical z/OS system are linked REFR? :-D -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 [EMAIL PROTECTED] http://www.phoenixsoftware.com/ ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
