Need clarification of VSAM FCT and DFHCSD relation

pkmurali · Active User Joined: 15 Dec 2005 Posts: 271

Dear All,

In my application i find few VSAM files used in CICS COBOL programs were not having DSN name defined. I used CEMT I FILE() command to check the presence of DSN name in the CICS region but i could not get the DSN name and FCT entries. I checked the file name in CSD file, dsn nsme is not present. Apart from FCT, is there anyway that VSAM file can be accessed ( i dont think so) since i am not a system programmer i need clarification on this Also i read through IBM manuals regarding dynamically defining FCT for VSAM, Is there any chance multiple filename can be defined for one VSAM DSN? Is there anyway to check the presence of DSN of VSAM apart from CEMT I FILE and searching in CSD?

Rohit Umarjikar · Posted: Sun Apr 10, 2016 6:10 am

Send an email to CICS Admin at your site. They should be able to help you.
Have you check the CICS JCL? you can override the DSNAME at run time by specifying the DD name and DSNAME for the file which will use the provided value.

pkmurali · Active User Joined: 15 Dec 2005 Posts: 271

Hi Rohit,

If CICS JCL dynamically overrides the DSN name, will be it impacts FCT? I will check the CICS JCL.

Eyal.ma · New User Joined: 05 May 2013 Posts: 5 Location: Israel

You need to understand that there are 3 places you can define a file. FCT, CSD and CICS JCL.

All those 3 options, are not dynamic. So any dynamic change, will not affect them the next time the CICS restarts.

A file can be defined multiple times with a different DSN name (CSD, FCT and JCL). The JCL dataset name definition takes precedence over the DSNAME of the FCT or CSD.

If you dynamically change the name of the dataset of the tile, next time the CICS restarts, if the definition is in the CICS JCL or the FCT, it will overwrite what was defined dynamically.
If the definition of the dataset name is in the CSD, it will be overwritten only if the CICS starts in COLD status (or initial).

I hope this helps.

pkmurali · Active User Joined: 15 Dec 2005 Posts: 271

The below is the CICS JCL, please let me know where can i find the VSAM file to be overridden?

Eyal.ma · New User Joined: 05 May 2013 Posts: 5 Location: Israel

What VSAM file are you looking for?

Also I'm trying to figure maybe I read what you wrote wrong.

When you are using CEMT I FILE you don't see the file at all, or you don't see the DSNAME filled?

If you do CEMT I FILE and you don't see the file you are looking for at all, most likely it was not defined in any of the 3 locations possible, and you or the CICS admin needs to define the file.

If you see the file but no DSNAME at all, it means that either the FCT or CSD did not specify a dataset name, and someone do needs to.

pkmurali · Active User Joined: 15 Dec 2005 Posts: 271

Hello Eyal.ma,

In CEMT I File() i didn't get the DSN name. I have mentioned already

Rohit Umarjikar · Posted: Mon Apr 11, 2016 8:33 pm

Always contact CICS support staff for these type of issues than making decisions based out of forum replies as they are not 100% true upon your shop standards.

Robert Sample · Posted: Mon Apr 11, 2016 9:26 pm

I echo Rohit's recommendation -- you REALLY need to contact your site support group. If, for example, your site is using MRO and you're looking at the TOR (Terminal-Owning Region) while the data set is defined in the FOR (File-Owning Region), then you won't necessarily see any link between the FCT and the DFHCSD entry -- partly because they are different CICS regions, and partly because the TOR and FOR could be using different DFHCSD data sets. And the data set name would be in the TOR, so you would not usually see it in the TOR.

Eyal.ma · New User Joined: 05 May 2013 Posts: 5 Location: Israel

pkmurali · Active User Joined: 15 Dec 2005 Posts: 271

I have checked all the regions CSD, all are region CICS JCL is representing the same CSD file.

Robert Sample · Posted: Fri Apr 15, 2016 8:34 pm

So what did your site support group tell you when you talked to them?

Rohit Umarjikar · Posted: Fri Apr 15, 2016 10:39 pm

pkmurali · Active User Joined: 15 Dec 2005 Posts: 271

Hi Rohita,

Could you please explain on data tables wrt to VSAM FCT? I have posted this to my support team.

pkmurali · Active User Joined: 15 Dec 2005 Posts: 271

I got it.. Data tables

www.ibm.com/support/knowledgecenter/SSGMCP_5.3.0/com.ibm.cics.ts.sysdefinition.doc/topics/dfha2_cics_datatables.html

Bill O'Boyle · Posted: Mon Apr 18, 2016 4:35 pm

Data Tables (a fancy name for a VSAM file) is used (in my opinion) as Read-Only as writing to it will defeat its overall purpose.

Rather than define the FCT entry as a data-table, define it to an efficient LSR Pool as well as efficient CISIZE's for data and index. Your CICS Sysprog would probably be the person to consult with on this matter.

Data-Tables are moved to extended-storage at CICS startup and therefore, accessing records from them is much more efficient, as most VSAM path logic is eliminated.

You should Google "CICS Data Tables" and learn more about them.

HTH....