Re: COBOL Compiler for Windows

On Tue, 29 Apr 2008 10:13:48 -0400, Graham Hobbs <ghobbs@xxxxxxxxxxx>
wrote:

I semi-expected your comments about CICS and DB2 but what's the
difference between KSDS and Indexed Sequential? For that matter what's
the diff between ESDS and 'flat or sequential' files?

I really should know this stufff but I don't!

It depends on the system. VSAM is a file management system that was
supposed to replace the three types of files that IBM already had on
mainframes (flat, indexed, and relative). In my experience it made
them more like the Univac 9030 file systems I was familiar with at the
time.

IDCAMS is the utility to run this file management system. But
people were already familiar with the non-managed systems, and the
only place I've seen ESDS files was where I implemented them myself -
to replace the 9030 functionality.

On the other hand, KSDS files had some significant performance
advantages over IBM's previous indexed file system, so it became the
standard in most shops. (Many shops have replaced visible KSDS by
databases (which sometimes use KSDS behind the scenes)).

Someone who works with alternative mainframe company's machines just
see different flavors of indexed files. Their companies didn't come
up with new names for their improvements in file handling.
.

Relevant Pages

  • Re: COBOL Compiler for Windows
    ... the diff between ESDS and 'flat or sequential' files? ... VSAM (the Very Silly Access Method) was a major leap up from ISAM (the ... KSDS was able to utilize the new VSAM ...
    (comp.lang.cobol)
  • Re: Dups In KSDS,ESDS
    ... Is there a standard way to handle "dups" if found in a KSDS, or an ESDS? ... KSDS is a keyed dataset, and by default CANNOT have a dupe, as it would ... ESDS is a non-keyed dataset, and as such has no true dupe, unless ...
    (bit.listserv.ibm-main)