If you were familiar with MVS when it was still marketed as MVS (MVS/SP,
MVS/XA, MVS/ESA), then you are probably aware that to actually have a
functional MVS system you had to have many additional essential products
installed along with MVS: JES2/3, VTAM, Assembler, DFP, TSO, ISPF,
RACF, DFDSS, compilers, SORT, other utilities, etc., etc. In the 1990's
to "simplify" things MVS was repackaged and marketed as "OS/390", which
included MVS integrated with the many IBM products that most
installations found essential, plus some additional components that IBM
considered strategic at the time (like TCPIP and POSIX support). There
were also optional, extra-charge products that could be ordered as part
of OS/390, and by ordering these with OS/390, installation was
simplified and there was greater assurance that the products were at a
maintenance level compatible with the rest of the system.
When MVS (and related products) evolved to where they required and
exploited the z-architecture mainframe extensions to the S/390 ESA
architecture (z900, z990, z9, etc.) , OS/390 evolved to a new name of
"z/OS". So, z/OS is the latest version of MVS together with some
minimal set of compatible products that make a functional MVS system in
a z-architecture mainframe environment.
Since different installations have different programming environments,
compilers like COBOL, C, PL/I, FORTRAN, are all optional and extra cost,
but integrated with z/OS if ordered. To support COBOL applications
you would need a COBOL compiler. CICS and DB2 are additional chargeable
products that are ordered and installed separate from z/OS; so to
support COBOL/CICS would require some flavor of CICS. And of course
there are still other vendor products on a typical z/OS system that are
not part of z/OS itself (like automated production batch job schedulers
and job restart managers). Everything required to run a basic batch
jobs is included with the base z/OS, but if the batch job stream expects
to run some special utility that is not part of the base z/OS
components, then some provision for that utility is required.
z/OS is strictly an IBM z-architecture mainframe operating system and
assumes that the hardware on which it is running supports the machine
instructions as defined in the z-architecture Principles of Operation
manual (which for application code is an upward-compatible extension of
the old S/360 POp), plus hardware-model-specific capabilities for
hardware recovery and hardware re-configuration which are probably not
documented outside of IBM. There is no version of z/OS that runs on any
other architecture (e.g., Intel or PowerPC). z/OS could in theory run
under a z-architecture emulator running on another architecture, but
there is currently no way to license z/OS for such an environment and
not much hope for that policy to change anytime soon.
Graham Hobbs wrote:
Dummy's question..
Have read some stuff about z/OS but is still not vibrantly clear to me
(likely me only), if batch OS/JCL streams and COBOL/CICS transactions
can run thereunder - in essence the MVS environment I worked in for so
many years.
Is it like a 'be all and end all' OS that supports the big mainframes,
reaches down to the midrange stuff and might ultimately dilute to
something like the old OS/2?
Might there be documents I could access to learn about this?
Haven't seen the subject expicitly spoken/written.
Thanks.
--
Joel C. Ewing, Fort Smith, AR [EMAIL PROTECTED]
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