John, ACCESS IS DYNAMIC has to do with specifying how the data set is to be processed: sequentially, randomly or both(DYNAMIC). Unless there has been changes to zOS regarding VSAM files this is the ways it has been since 1987 of earlier.
On Mon, Mar 1, 2010 at 4:00 PM, 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: > > 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. > > 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? > > John McKown > Systems Engineer IV > IT > > Administrative Services Group > > HealthMarkets(r) > > 9151 Boulevard 26 * N. Richland Hills * TX 76010 > (817) 255-3225 phone * (817)-961-6183 cell > [email protected] * www.HealthMarkets.com > > Confidentiality Notice: This e-mail message may contain confidential or > proprietary information. If you are not the intended recipient, please > contact the sender by reply e-mail and destroy all copies of the original > message. HealthMarkets(r) is the brand name for products underwritten and > issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake > Life Insurance Company(r), Mid-West National Life Insurance Company of > TennesseeSM and The MEGA Life and Health Insurance Company.SM > > > ---------------------------------------------------------------------- > 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 > ---------------------------------------------------------------------- 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
