The "H" in "HBUFN*" indeed stands for "Hiperspace". These spaces still exist and always were distinct from Dataspaces. VSAM does not use Dataspaces.
Nowadays Hiperspaces will be backed by real memory; They remain a valid architectural concept / implementation. And will damped autocorrupt boldly well stop changing "Hiperspace" to "Hyperspace". Aargh! š There IS still a use case, I suppose: Virtual Storage Constraint Relief. Better, though, to put VSAM LSR buffers above the line (and below the bar). Thanks to Allan Winston for tapping me on the shoulder as one of the authors of the SG24-2557 "Parallel Sysplex Performance Topics" Redbook - where we discussed this sort of thing. (Most of this Redbook is still valid.) And, Peter, you're not alone in the "small extended private" club; I saw a similar number in another customer the other day. I am working with someone right now on a presentation we're tentatively calling "Virtual Storage After All These Years". No promises and I mention that merely to test the assumption that virtual storage remains a hot topic - whether some customers realise it or not. Cheers, Martin From: IBM Mainframe Discussion List <[email protected]> on behalf of Farley, Peter <[email protected]> Date: Saturday, 30 May 2026 at 01:27 To: [email protected] <[email protected]> Subject: [EXTERNAL] Re: What is the SUBSYS=(BLSR,...) current implementation for HBUFND and HBUFNI allocations? Yes, I just found my copy of that manual as well (I should have remembered I had it around somewhere or other), and it does day the HBUFNx buffers are (or can be if you are authorized to do so) allocated in a āVSAM hiperspaceā. Sorry for wasting bandwidth here when I should have RTFMāed first. Peter From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Michael Watkins Sent: Friday, May 29, 2026 8:09 PM To: [email protected] Subject: Re: What is the SUBSYS=(BLSR,...) current implementation for HBUFND and HBUFNI allocations? I have a .pdf copy of the 1994 IBM publication 'MVS Programming: Batch Local Shared Resources Subsystem Guide', if you'd like to share your email address, Peter Farley. -----Original Message----- From: IBM Mainframe Discussion List <[email protected]<mailto:[email protected]>> On Behalf Of Farley, Peter Sent: Friday, May 29, 2026 5:52 PM To: [email protected]<mailto:[email protected]> Subject: Re: What is the SUBSYS=(BLSR,...) current implementation for HBUFND and HBUFNI allocations? CAUTION: This email originated from outside of the Texas Comptroller's email system. DO NOT click links or open attachments unless you expect them from the sender and know the content is safe. After I hit send on this question, I thought of another possible implementation ā are HBUFNx buffers perhaps allocated in a separate data space below the 2G bar? If so are there any measurements I could view to tell me the actual usage/performance affect for such buffers? Peter From: IBM Mainframe Discussion List <[email protected]<mailto:[email protected]>> On Behalf Of Farley, Peter Sent: Friday, May 29, 2026 6:41 PM To: [email protected]<mailto:[email protected]> Subject: What is the SUBSYS=(BLSR,...) current implementation for HBUFND and HBUFNI allocations? I know that for BLSR the HBUFND and HBUFNI parameters originally allocated memory in "extended storage" when that actually existed as a hardware option. In z/OS today (V3.1), given that RMODE31=ALL is also specified, are HBUFND and HBUFNI buffers allocated above the 16M line but below the 2G bar just like BUFND and BUFNI, or are HBUFNx buffers allocated above the 2G bar? I am trying to determine if it is worth using BLSR HBUFNx parameters for NON-extended VSAM KSDS reference files on somewhat memory-constrained below 2G systems (available PRIVATE < 1148M) for batch applications that use lots of reference data READ's, or instead should I just increase the BUFND and BUFNI values within the existing memory constraints below 2G? 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 [email protected] with the message: INFO IBM-MAIN Unless otherwise stated above: IBM United Kingdom Limited Registered in England and Wales with number 741598 Registered office: Building C, IBM Hursley Office, Hursley Park Road, Winchester, Hampshire SO21 2JN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
