Ok, I was not aware of that fact. Thank you.
It is indeed a clever decision to make such "Access Method Services"
part of the operating system, because this way a standard method is defined
and all other languages or systems can use it. For example DB2, which
uses VSAM as access method in several respects. (Even ORACLE is
using VSAM, when it runs on z-Hardware, IIRC ... and so ORACLE
benefits from VSAM improvement done to support DB2).
LE comes to mind; such services, available to all programming languages,
should also be part of the operating system.
The German Telefunken mainframe TR440's operating system BS3 also
had keyed file access services (different types) and a common run time
environment
for all languages (ALGOL, FORTRAN, PASCAL, PL/1, COBOL, BCPL, ...).
And it had (in the 1970s) a common method of storing
diagnose information at compile time, helping the runtime environment
to write helpful dump information in the case of an abend. The variables
were all shown in source language syntax; there was no need to look
at hex storage dumps. This whole technique was part of the operating
system, too. (Even interactive symbolic debugging ... using teletypes and
very basic display terminals ... was possible).
As I said, the opinions what a operating system should do, changed
over time, even at IBM. There was never such support for programmers
as I outlined it above in IBM systems, although in the last ten years or
so,
LE developed in this direction, too.
As you can see, I am no advocat of Windows etc.; the support for
programmers there is non-existent ... if you need it, you have to buy
expensive compiler suites from M$ ... Linux and Unix is different, of
course.
It is a big problem in Windows (and DOS etc. in previous times), that the
compilers all had different call sequences and parameter passing
mechanisms,
so that it was not possible to mix languages and/or compilers. Such things
as common linkage conventions are very helpful (although there are some
problems at the z/Arch, too).
I have a vision how an ideal operating system should look like from the
programmers point of view ... and that vision is very much inspired by my
old experience of the 1970s operating system BS3. Sorry.
Kind regards
Bernd
Am 21.04.2014 07:14, schrieb Timothy Sipples:
Bernd Oppolzer asks:
BTW: is VSAM part of the operating system?
Yes. VSAM is certainly a standard, included, essential, no additional
charge feature within the base z/OS and z/VSE operating systems.
IBM first introduced VSAM (in a more basic form of course) back in the
1970s for DOS/VS, OS/VS1, and OS/VS2 ("Access Method Services"). I don't
think VSAM was ever separately licensed, but someone can correct me if I'm
mistaken on that point.
z/VM's CMS and MUSIC/SP also support VSAM, also in base. Base z/TPF does
also, though it collaborates with z/OS to get the job done. Hitachi's and
Fujitsu's Japanese mainframe operating systems (VOS3, MSP, XSP) also
support VSAM -- not a great surprise given their heritages.
Perhaps you're thinking of Transactional VSAM (DFSMStvs)? Transactional
VSAM is an optional addition available for z/OS. (VSAM RLS is part of base
z/OS.)
--------------------------------------------------------------------------------------------------------
Timothy Sipples
IT Architect Executive, zEnterprise Industry Solutions, AP/GCG/MEA
E-Mail: [email protected]
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