I don't quite understand this thread, but I find it interesting in that I'd like to understand it.
Are you saying, that you can put some sort of "lock" on a control block, so that when you update it, you know that nobody else has updated it? I am not sure if this is apples and giraffes, but I wrote a Rexx exec and ISPF panel to show ASCB and related control blocks for a given job that shows all about timeouts. I hit the enter, and my Rexx and ISPF fields change accordingly. Sometimes I hit enter and see weird garbage in there. No matter. I just hit enter again and all is well. I assume the garbage in some of the fields is due to the control blocks being in some unknown state. But if I hit enter and see, for example, 5 things, and somebody updates and adds one or takes one away, then when I hit enter again, I'll see the updated list. I see how long I have to wait for a 522, or I see that the job is exempt from timeout. That won't change. If someone adds something new just a millisecond from when I look for it, how is that different from updating a database table? You might say to lock it for update. I may say that I want to read the row, then lock it and update it just if it is has changed. In that case I know if it has changed. I'm not trying to be smart, I only want to understand what is the real issue. The only thing I can think of is that if multiple control blocks are chained together, or somehow are related, that I don't want to read one while the other is updated. Can I read these control blocks with Rexx? If so, maybe I'll give it a go when I have some free moments. Kind regards, Lindy -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of John Gilmore Sent: Tuesday, November 13, 2012 11:38 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: "New" way to do UCB lookups Jim Mulder's point is very well taken indeed. Traversing a dynamic list without serialization on the assumption that since you do not plan to change it no one else will is a mug's game. John Gilmore, Ashland, MA 01721 - USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
