DCBE allows you to stick buffers above the line. I remember (in 1993 or thenabouts)Jeff Berger presenting on Stripes Performance and he had run experiments that showed you needed to up the buffering to get the best sequential speed with Stripes. DCBE, used right, was a way to do that.
So DCBE DOES have value. The question becomes what the runtime (such as it might be) does to exploit DCBE. Martin Packer, zChampion, Principal Systems Investigator, Worldwide Cloud & Systems Performance, IBM +44-7802-245-584 email: [email protected] Twitter / Facebook IDs: MartinPacker Blog: https://www.ibm.com/developerworks/mydeveloperworks/blogs/MartinPacker Podcast Series (With Marna Walle): https://developer.ibm.com/tv/mpt/ or https://itunes.apple.com/gb/podcast/mainframe-performance-topics/id1127943573?mt=2 From: Joseph Reichman <[email protected]> To: [email protected] Date: 15/02/2017 16:49 Subject: Re: QSAM using DCBE macro Sent by: IBM Mainframe Discussion List <[email protected]> Thanks > On Feb 15, 2017, at 10:55 AM, Charles Mills <[email protected]> wrote: > > Just having some fun with your nostalgic terminology. > Isn't the Large Block Interface documented? > Why all the concern with the amount of data read at once? Why not just let QSAM do its thing and then if you have performance issues, look for the best way to address the actual issues? > > CharlesSent from a mobile; please excuse the brevity. > -------- Original message --------From: Reichman Joseph <[email protected]> Date: 2/15/17 7:40 AM (GMT-08:00) To: [email protected] Subject: Re: QSAM using DCBE macro > Thanks > > > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Charles Mills > Sent: Wednesday, February 15, 2017 10:39 AM > To: [email protected] > Subject: Re: QSAM using DCBE macro > > At its core, yes. > > CharlesSent from a mobile; please excuse the brevity. > -------- Original message --------From: Steve Smith <[email protected]> Date: 2/15/17 7:26 AM (GMT-08:00) To: [email protected] Subject: Re: QSAM using DCBE macro Is this supposed to be a poem? > > sas > > On Wed, Feb 15, 2017 at 10:00 AM, Joseph Reichman <[email protected]> > wrote: > >> Hi >> >> Previously I had asked if there were any advantages to using BSAM over >> QSAM >> >> I was told there were very little >> >> And with a high price of coding complexity >> >> Now I wonder about using the DCBE macro >> >> With QSAM if there are any advantages I.E. >> >> Using the large block interface >> >> Would this mean that one QSAM "GET" >> >> Would read more data at one time into core >> >> Thanks >> >> ---------------------------------------------------------------------- >> For IBM-MAIN subscribe / signoff / archive access instructions, send >> email to [email protected] with the message: INFO IBM-MAIN >> > > > > -- > sas > > ---------------------------------------------------------------------- > 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 > > ---------------------------------------------------------------------- > 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 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
