Portal | Manuals | References | Downloads | Info | Programs | JCLs | Master the Mainframes
IBM Mainframe Computers Forums Index
 
Register
 
IBM Mainframe Computers Forums Index Mainframe: Search IBM Mainframe Forum: FAQ Memberlist Usergroups Profile Log in to check your private messages Log in
 

 

Use ISAM access method in COBOL

 
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> COBOL Programming
View previous topic :: :: View next topic  
Author Message
Chetan Kumar

New User


Joined: 03 Dec 2012
Posts: 35
Location: India

PostPosted: Tue Oct 13, 2015 10:28 pm    Post subject: Use ISAM access method in COBOL
Reply with quote

Hi All,

Is the usage of ISAM and KSDS in the cobol program is same?
Can we use ISAM access method in COBOL? If so, are there any changes to be made to the JCL to use the file or is it similar to KSDS file.

Bascially I want to know the difference between ISAM and KSDS (VSAM) from the programmers perspective.
Back to top
View user's profile Send private message

Robert Sample

Global Moderator


Joined: 06 Jun 2008
Posts: 7904
Location: Bellevue, IA

PostPosted: Tue Oct 13, 2015 10:51 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

Are you talking about ISAM the generic indexed sequential access method, or are you talking about ISAM the IBM implementation? IBM stopped supporting ISAM many years ago as it was replaced by VSAM KSDS. VSAM KSDS is an indexed sequential access method. If your site is still using ISAM as implemented by IBM (and very few, if any, will be) -- you will need to discuss your questions and needs with your site support group as I'm sure there would have been numerous modifications to allow unsupported software to work on a current machine. If you just want to know about VSAM KSDS as an indexed sequential access method, there's a Redbook (http://www.redbooks.ibm.com) called VSAM Demystified that is quite good at explaining VSAM.
Back to top
View user's profile Send private message
Chetan Kumar

New User


Joined: 03 Dec 2012
Posts: 35
Location: India

PostPosted: Tue Oct 13, 2015 11:02 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

It's about generic indexed sequential access method.
Back to top
View user's profile Send private message
Bill Woodger

DFSORT Moderator


Joined: 09 Mar 2011
Posts: 7223

PostPosted: Tue Oct 13, 2015 11:12 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

And what specifically do you mean by that?
Back to top
View user's profile Send private message
Chetan Kumar

New User


Joined: 03 Dec 2012
Posts: 35
Location: India

PostPosted: Thu Oct 15, 2015 12:47 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

I want to know how the ISAM access method works inside Cobol Program. It is similar to KSDS or does there are changes in coding for accessing and to perform other operations.
Back to top
View user's profile Send private message
Bill Woodger

DFSORT Moderator


Joined: 09 Mar 2011
Posts: 7223

PostPosted: Thu Oct 15, 2015 1:13 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

If you look at an Enterprise COBOL Language Reference, do you see any specific treatment of VSAM-as-ISAM data?

Didn't the vendor let your client know, before the product was licensed? (If not, I've got a large bridge I'd like to sell to the client).

Have you just plain tried it? Attempted to locate documentation of the product? Done any search-engineing?
Back to top
View user's profile Send private message
Chetan Kumar

New User


Joined: 03 Dec 2012
Posts: 35
Location: India

PostPosted: Fri Oct 16, 2015 11:58 am    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

Basically I'm not getting required info. I searched for ISAM and it's use.. but I didn't get proper results for us of ISAM access methond in COBOL program.

Many docs say it's very similar to VSAM. Bascially VSAM is enhanced form of ISAM. But coding usage, I'm not getting clear picture.
Back to top
View user's profile Send private message
enrico-sorichetti

Global Moderator


Joined: 14 Mar 2007
Posts: 10201
Location: italy

PostPosted: Fri Oct 16, 2015 12:35 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

if You look at it from the IBM point of view
ISAM is an old access method/dataset organisation NO LONGER supported/provided/implemented

so Your question is a moot point

if on the other side You heard the word from some software provider ask them.

if You are curious about old ISAM just search bitsavers
Back to top
View user's profile Send private message
Bill Woodger

DFSORT Moderator


Joined: 09 Mar 2011
Posts: 7223

PostPosted: Fri Oct 16, 2015 12:57 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

Read Robert's original post. In your case, you are almost certainly talking about something other than KSDS-is-improved-ISAM. I've never used ISAM-ISAM, and I started a long time ago.

Just code it as a KSDS in your program, run your program.
Back to top
View user's profile Send private message
PeterHolland

Global Moderator


Joined: 27 Oct 2009
Posts: 2422
Location: Netherlands, Amstelveen

PostPosted: Fri Oct 16, 2015 2:06 pm    Post subject:
Reply with quote

Look here :

http://www-01.ibm.com/support/knowledgecenter/SS6SG3_4.1.0/com.ibm.entcobol.doc_4.1/MG/igymch1013.htm
Back to top
View user's profile Send private message
Chetan Kumar

New User


Joined: 03 Dec 2012
Posts: 35
Location: India

PostPosted: Fri Oct 16, 2015 7:05 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

Still some applications use OS/VS COBOL and ISAM files as the access method. So basically I want to know how to use ISAM files in OS/VS COBOL programs which runs on LINUX as the platform.

I appreciate if you can provide any docs,links etc
Back to top
View user's profile Send private message
enrico-sorichetti

Global Moderator


Joined: 14 Mar 2007
Posts: 10201
Location: italy

PostPosted: Fri Oct 16, 2015 7:35 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

Quote:
Still some applications use OS/VS COBOL and ISAM files as the access method.


hard to believe ...


Quote:
So basically I want to know how to use ISAM files in OS/VS COBOL programs which runs on LINUX as the platform.


same comment as above

if You have an old mvs system which still has ISAM You will have to find out Yourself

the chances of getting help on a forum for such an issue is pretty slim

the same for people spending time to research for You ...

You did not notice that I suggested to search bitsavers,
it is an archive of the manuals for older systems
Back to top
View user's profile Send private message
Bill Woodger

DFSORT Moderator


Joined: 09 Mar 2011
Posts: 7223

PostPosted: Fri Oct 16, 2015 7:55 pm    Post subject: Reply to: ISAM and KSDS (VSAM)
Reply with quote

So after all this time you are really talking about ISAM-as-ISAM.

Wow. You'd better find your hardcopy OS/VS COBOL manual. There's lots of things different between OS/VS COBOL and Enterprise COBOL. Lots.

You get some idea from Peter's prescient link.
Back to top
View user's profile Send private message
PeterHolland

Global Moderator


Joined: 27 Oct 2009
Posts: 2422
Location: Netherlands, Amstelveen

PostPosted: Fri Oct 16, 2015 10:41 pm    Post subject:
Reply with quote

Quote:
ISAM files in OS/VS COBOL programs which runs on LINUX as the platform.


Linux and IBM ISAM? Impossible, did you drink the wrong tea?
Back to top
View user's profile Send private message
steve-myers

Active User


Joined: 30 Nov 2013
Posts: 460
Location: The Universe

PostPosted: Fri Oct 16, 2015 11:58 pm    Post subject:
Reply with quote

Well, it's certainly possible to simulate ISAM within the file system. Effectively, that's what VSAM KSDS is doing in the mainframe. What the Cobol library is doing for the simulated ISAM is up to the writers of the library; you have to consult its documentation.
Back to top
View user's profile Send private message
Pete Wilson

Active User


Joined: 31 Dec 2009
Posts: 437
Location: London

PostPosted: Sat Oct 17, 2015 1:18 am    Post subject:
Reply with quote

Note: z/OS no longer supports indexed sequential (ISAM) data sets. Before migrating to z/OS V1R7, convert your indexed sequential data sets to key sequenced datasets.

I'm wondering if you're confusing ISAM with IAM (Innovation Access Method) which is kind of a progession of ISAM supported by Innovation Data Processing, and which is a very popular alternative performance access method for CICS datasets that would normally be VSAM format.
Back to top
View user's profile Send private message
Rohit Umarjikar

Senior Member


Joined: 21 Sep 2010
Posts: 1609
Location: NY,USA

PostPosted: Sat Oct 17, 2015 3:12 am    Post subject:
Reply with quote

VSAM is the term IBM uses for one of its mainframe file systems (Virtual Sequential Access Method). It supports three formats: Indexed, Relative and Sequential access modes. Are you refering to converting an old IBM ISAM format to VSAM? If so, you would probably just unload the ISAM file to a sequential dataset and then use the IDCAMS services to define the new VSAM file and load the sequential file using Repro.

http://www-01.ibm.com/support/knowledgecenter/#!/SS6SG3_3.4.0/com.ibm.entcobol.doc_3.4/tpvsm02.htm

So answer to your questions, yes both are same infact VSAM is much better No changes required from programming stand poing, try and run with both the files instead of making gusses or forum answers.

Please Google it for more differences and the use.

Are you working on MF cobol or is it just another interview question?
Back to top
View user's profile Send private message
Robert Sample

Global Moderator


Joined: 06 Jun 2008
Posts: 7904
Location: Bellevue, IA

PostPosted: Sat Oct 17, 2015 11:26 pm    Post subject:
Reply with quote

Quote:
It supports three formats: Indexed, Relative and Sequential access modes.
Rohit, don't forget Linear is now allowed with VSAM so "three formats" is no longer correct.
Back to top
View user's profile Send private message
Pete Wilson

Active User


Joined: 31 Dec 2009
Posts: 437
Location: London

PostPosted: Sun Oct 18, 2015 12:30 am    Post subject:
Reply with quote

and VRRDS
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> COBOL Programming All times are GMT + 6 Hours
Page 1 of 1

 

Search our Forum:

Similar Topics
Topic Author Forum Replies Posted
No new posts IMS DC screen Access sivasaras IMS DB/DC 3 Fri Nov 18, 2016 6:38 pm
This topic is locked: you cannot edit posts or make replies. RANDOM Function in COBOL swapnil781 COBOL Programming 2 Tue Nov 15, 2016 6:17 pm
No new posts Regarding COBOL Stored Procedure opti... selvamsrinivasan85 DB2 4 Fri Nov 04, 2016 8:57 pm
No new posts COBOL Version 6.1 Virendra Shambharkar COBOL Programming 5 Tue Nov 01, 2016 11:24 am
No new posts Cobol list of programs being called biswajit.dattagupta COBOL Programming 5 Tue Nov 01, 2016 2:10 am


Facebook
Back to Top
 
Mainframe Wiki | Forum Rules | Bookmarks | Subscriptions | FAQ | Tutorials | Contact Us