If possible, convert the file to extended format and use system managed buffering (covered in VSAM Demystified). It's easier to implement than BLSR. It will probably use more memory than BLSR, but that can be controlled easily if necessary. I've had great results with it. The programmers of the first application I tried it on were so happy they bought me a fruit basket for Christmas. ;-)
db -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Farley, Peter x23353 Sent: Monday, March 02, 2009 6:53 PM To: IBM-MAIN@bama.ua.edu Subject: Re: VSAM BLSR > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On > Behalf Of David Speake > Sent: Monday, March 02, 2009 6:29 PM > To: IBM-MAIN@bama.ua.edu > Subject: VSAM BLSR > > I have a customer with what they perceive as a memory problem, Reviewing > their JCL I feel otherwise. There are some VSAM BLSR values that I > seriously question. I have written a response but am now having insecurity > issues - its been a while and although "VSAM Demystified" and "DFSMS > Using Data Sets" seem to confirm most of my material, I'd sure like to > see a z/OS R1.9 VSAM PLM for a few hours. > > I have my beach towel handy in case the egg on my face get real deep. > Comments and pointers appreciated. I would agree that the BUFSI/BUFSD specifications do not appear to be helpful. I can't confirm if there would in fact be wasted memory, but my question to the customer would be, "Why specify BUFSI/BUFSD at all? Why not let the system use the actual values for the buffer sizes as it finds them?". Especially because they are, in fact, the same for both files. I can confirm that the BUFND specifications are in fact cumulative. When we first implemented a huge application with BLSR in the OS390 days, we had to be careful that for all SHRPOOL's added together, all the BUFND's times BUFSD did not exceed the 2GiB region limit. This was for RRDS's, so no BUFNI was involved, though I would assume the same is true for BUFNI as for BUFND. HTH Peter This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu 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 lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
