Joseph, I believe that LBI is only for tape inputs and outputs. You can speed up your processing easier by using either the older BLSR buffering subsystem or better the newer SMB buffering system. See the JCL reference manual for SMB parameters.
Allocate as much REGION as your installation will allow (some installations limit the maximum any job without special authorization may use, even sometimes production jobs). Use BLSR or SMB to allocate as many buffers as will fit in the REGION size you can allocate. I have seen substantial decreases in run time using these techniques with very large sequential files. I would also recommend using at least software compression or better hardware compression (if your CPU has it) for your large sequential files. The CPU time used for compression and decompression will sometimes be offset by decreases in elapsed time due to reduced I/O burdens for the compressed data, especially if you have hardware compression available. HTH Peter -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Joseph Reichman Sent: Monday, March 1, 2021 1:14 PM To: [email protected] Subject: Re: Large block interface for VB EXTERNAL EMAIL Who uses tape I went to bsam trying to speed up my application wonder if going to bsam Does anything positive for me > On Mar 1, 2021, at 1:10 PM, Paul Gilmartin > <[email protected]> wrote: > > On Mon, 1 Mar 2021 11:24:57 -0500, Joseph Reichman wrote: > >> It disk then documentation says the system only supports tape at this time >> is That true ? >> > Have you any reason to doubt it? > > I suspect it's a hardware limitation. > >>>> On Mar 1, 2021, at 11:22 AM, Paul Gilmartin wrote: >>> >>> On Mon, 1 Mar 2021 09:12:59 -0500, Joseph Reichman wrote: >>> >>>> I have 100 files concatenated that are normally processed by qsam >>>> with a lrecl 31996 and blksize 32000 >>>> >>>> Since processing takes a long time I was looking to speed things up >>>> by specifying a blksize of 320000 in the DCBE >>>> >>> What device type? >>> >>>> After the first read using bsam read macro I looked at the first 4 >>>> bytes ( Block descriptor word ) and it was x’7C4A’ which is 31,888 >>>> which seemed to me that it was still processing blksize of 32,000 > > -- gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN 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 [email protected] with the message: INFO IBM-MAIN
