This was actually kind of fun to dig into... I knew a lot of what was going on here, but I had to try it out myself to put all of the puzzle pieces together.
I'm far from being an expert on ENQ, so I don't know all of the reasons why ENQ upgrade behaves the way it does. But deadlocks are at least part of the reason. It doesn't take a lot of effort to come up with some scenarios where ENQ would have to fail an upgrade request, such as two shared holders both requesting upgrade to exclusive. At least one of them has to give up its shared access for anything to move forward. And... >And the lesson here is that if you have a job that requires a DISP=OLD on a >relative GDG in some step, then the only way to avoid the IEF211I is for >the FIRST use of the same relative GDG to also be DISP=OLD. I think that's right, that's the only way I can think of to definitively prevent it. -Scott Ballentine, IBM z/OS Device Allocation [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
