Data no longer must be read into buffers in 31-bit storage. You can now do I/O directly into or out of 64-bit virtual addresses with real backing also in 64-bit addressing. I have been doing it for several years with BAM (Bill's Access Method) that uses I/O services at a level lower than EXCP. I'm sure that DB2 and other strategic products of IBM are also doing I/O with 64-bit buffer addresses.
Bill Fairchild Programmer Rocket Software 408 Chamberlain Park Lane * Franklin, TN 37069-2526 * USA t: +1.617.614.4503 * e: bfairch...@rocketsoftware.com * w: www.rocketsoftware.com -----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of Gainsford, Allen Sent: Wednesday, September 12, 2012 3:58 PM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Data spaces vs hiperspaces >That said, there are circumstances where the opposite may be true: that a >hyperspace may provide better performance than 64-bit storage. I had a case >recently, with a program that generates large amounts of data that it needs to >hold temporarily in storage. I tried both ways, and found that a hyperspace >gave better performance. >The reason, I eventually decided, was that the data had to be initially read >from a dataset -- and thus had to be read into 31-bit storage -- and later >written back to a dataset -- again, having to be written from 31-bit storage. >When it came to storing the data away, the overhead of copying it above the >bar, and later copying it back again, was greater than the overhead of leaving >it where it was and using a hyperspace. >If I'd been able to create, and later consume, the data entirely in 64-bit >storage, the reverse would probably have been true. >Allen Gainsford Info Developer, Banking Shared Services HP Enterprise Services (South Pacific)
