Paul Gilmartin wrote:
Likewise, if RET=CHNG were not available, you could equally well simply DEQ and re-ENQ with EXCL scope.
No. Holding a shared ENQ prevents others from acquiring an exclusive ENQ on the same resource and modifying it. To maintain the integrity of the resource, you use RET=CHNG to upgrade from shared to exclusive without losing control. If you were required to DEQ and then re-ENQ to perform the upgrade, you would lose control of the resource between the time you inspected it and the time you had the necessary serialization to update it. In the worst case scenario, someone else could change (or even delete) the resource in-between!!
-- 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
