On Mon, 1 Mar 2010 15:00:37 -0600 "McKown, John" <[email protected]> wrote:
:>Almost every VSAM file SELECT we have is coded as below: :>SELECT HISTORY-FILE :> ASSIGN TO GCR05KSD :> RECORD KEY IS HST05-KEY :> ORGANIZATION IS INDEXED :> ACCESS IS DYNAMIC :> FILE STATUS IS HISTORY-STATUS. :>That is, with ACCESS IS DYNAMIC. This despite the fact that the file is opened only once, for INPUT: Not relevant. ACCESS DYNAMIC can be fully appropriate with OPEN INPUT. :> OPEN INPUT HISTORY-FILE. :>I'm concerned that this results in less efficient I/O. In particular, that it results in more CPU usage than if the ACCESS were changed from DYNAMIC to SEQUENTIAL. The READ is of the form: :>READ HISTORY-FILE NEXT RECORD INTO HISTORY-RECORD :> AT END MOVE 'Y' TO HISTORY-FILE-EOF-SW. If every single READ is NEXT RECORD it would appear to be unnecessary. :>From what I can tell, sometime in the past, some programming manager made ACCESS IS DYNAMIC a required standard for all VSAM files. I guess for "flexibility". Does this make any significant difference in terms of CPU usage at all? Makes it easier to add random reads. -- Binyamin Dissen <[email protected]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies. ---------------------------------------------------------------------- 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
