In TSS/360, VPAM datasets can have both sequential and index sequential
members; you can read and write withing a member either sequentially or by key,
including inserting a new record between existing members. VIPAM is a
colloquial term for a VPAM dataset containing VIS members. From the
documentation:
Three special Data Management Access methods -- the virtual Access
Methods (VAM)-- have been provided with TSS. They are specifically
designed for a time-sharing environment and are used to read and write
data to and from direct access storage devices. For all three of the
VAM access methods, the data set management (for example, formatting)
is performed in virtual storage -- using virtual addresses that are
part of the user's virtual storage address space -- although physical
device management (e.g., I/O) is performed by system programs in
resident storage. Each access method provides access and processing
capabilities for data sets organized in a specific manner.
* sequentially (Virtual Sequential Access Method -- VSAM)
* indexed sequential (Virtual Indexed Sequential Access Method --
VISAM)
* partitioned (Virtual Partitioned Access Method -- VPAM)
In TSS, data sets organized for processing by one of the virtual
access Methods are generally referred to as VAM data sets.
and
Partitioned Organization
A data set with partitioned organization has elements, or
members, that are other data sets; these elements are in either
sequential or indexed organization.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
________________________________________
From: IBM Mainframe Discussion List [[email protected]] on behalf of
Clark Morris [[email protected]]
Sent: Monday, June 29, 2020 11:15 PM
To: [email protected]
Subject: Re: Virtual SHARE Ageenda
[Default] On 29 Jun 2020 18:05:01 -0700, in bit.listserv.ibm-main
[email protected] (Seymour J Metz) wrote:
>Re FBA, they did it for other systems, and TSS/360 used page formatted volumes
>for everything except compatibility volumes, so from a technical perspective
>it's a no brainer, although direct use of SCSI DASD might make more sense
>these days. Politically, it's a thorny issue. I'd love to see them extend VSAM
>to the level of TSS while they're at it, e.g., VIPAM.
What is the logical difference between VPAM (found it in a TSS360
description) and PDSE except PDSE is an add-on (my opinion of the
decision maker who decreed that PDSE or at least a read-only subset
didn't need to be available for SYS1.PARMLIB, SYS1.NUCLEUS and
SYS1.LPALIB is complete contempt)?
Clark Morris
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