Hi: Just to add some additional comments to this item:
The Hursley staff has stated at several conferences I have attended (SHARE and the CICS Technical Conference) that a TCB switch (e.g., QR to L8 (DB2)) within CICS takes around 2000 instructions or a round trip 4000 instructions. It would seem to me that an I/O operation is more complex than a TCB switch because it involves virtual storage to real conversion, fixing of pages and interrupt processing which involves state changes in the machine which affect the contents of the TLB (Translation Look-Aside Buffer re-population) etc. It would be interesting to have someone in the Capacity Planning area that could provide some input as to how much increase, if any, in operating system area occurs from one release to another. There are some new things in the I/O area versus 15-20 years ago that may increase (PAV) or reduce the number of instructions in the supervisor. Mark Thomen from VSAM monitors this list. Maybe he could shed some information as to how VSAM works so that we can all benefit from his knowledge and maybe help in answering the original question. Regards, Gene ---------------------------------------------------------------------- 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
