IBM Mainframe Forum

by **VIJAY1** » Mon Nov 19, 2012 3:17 pm

Can some one explain me where dfhcommarea comes into use while programming with an example..
I understood theoritically but coming to the application part,i am not positive.
Thanks in advance.

by **Robert Sample** » Mon Nov 19, 2012 3:34 pm

Your question is so broad as to be meaningless. DFHCOMMAREA is, in general, used by an application program (or programs) in a CICS system for transferring data between programs. What data will depend entirely upon the application.

One common use with pseudo-conversational programs is to indicate what the program needs to do. The program may start the PROCEDURE DIVISION by testing EIBCALEN and if it is zero, send a map and then EXEC CICS RETURN TRANSID('XXXX') COMMAREA(<working-storage area>) so when the terminal user hits the enter (or other attention) key and the program starts again EIBCALEN will not be zero and the program logic can then receive the map sent the first time through the code.

by **c62ap90** » Tue Nov 20, 2012 6:10 am

Robert is correct. The question is so broad it's hard to give a specific answer. Here is however a snippet of code to possibly put DFHCOMMAREA in context.
You may notice "MOVE DFHCOMMAREA TO WS-COMMAREA" {Linkage to WS}. This is not really needed. You can work completely (more or less) out of DSHCOMMAREA for passing information but I always liked the two for before/after comparisions if needed.
As Robert mentioned - DFHCOMMAREA is for passing data.

Select all

01 FILLER PIC X(30) VALUE 'WS-COMMAREA BEGINS HERE'.
01 WS-COMMAREA.
10 WS-COMM-XXXX-TRANSID PIC X(04).
10 WS-COMM-PROCESS-SW PIC X(01).
88 WS-COMM-FIRST-TIME-IN VALUE '0'.
88 WS-COMM-REENTRY VALUE '1'.
88 WS-COMM-REENTRY-ERROR VALUE 'E'.
EJECT
COPY DFHAID.
EJECT
COPY DFHBMSCA.
EJECT
01 FILLER PIC X(23) VALUE 'pgm name WS ENDS HERE'.
EJECT

*---------------------------------
*
LINKAGE SECTION.
*
*---------------------------------
*
CICS 01 DFHCOMMAREA.
CICS 10 LS-COMM-XXXX-TRANSID PIC X(04).
CICS 10 LS-COMM-PROCESS-SW PIC X(01).
CICS 88 LS-COMM-FIRST-TIME-IN VALUE '0'.
CICS 88 LS-COMM-REENTRY VALUE '1'.
CICS 88 LS-COMM-REENTRY-ERROR VALUE 'E'.

EJECT
CICS PROCEDURE DIVISION USING DFHEIBLK
CICS DFHCOMMAREA.
*****************************************************************
* P R O C E D U R E D I V I S I O N *
*****************************************************************

*--- CLEAR SCREEN AND DISPLAY END MESSAGE AT TOP OF SCREEN.
CICS IF (IEBAID = DFHCLEAR OR
CICS DFHPF3)
GO TO 999-END-SESSION
END-IF.

CICS MOVE DFHCOMMAREA TO WS-COMMAREA.

*--- TRAP GENERAL ERRORS
CICS EXEC CICS HANDLE CONDITION
CICS ERROR (900-SYSTEM-ERROR)
CICS LENGERR (915-LENGTH-ERROR)
CICS MAPFAIL (920-MAPFAIL-ERROR)
END-EXEC.

*--- INITIALIZE MAP/SCREEN
MOVE LOW-VALUES TO XXXXXXXO.
EJECT
*--- MAP XXXXXXXX
EVALUATE WS-COMM-PROCESS-SW

WHEN '1'
*--- RE-ENTRY
MOVE '004' TO WS-HOLD-PARAGRAPH-NUM
PERFROM 810-RECEIVE-MAP-XXXXXXXX

EVALUATE EIBAID

WHEN DFHPF5
etc...

by **mongan** » Tue Nov 20, 2012 1:34 pm

c62ap90 what you said is very dangerous

. You can work with the DFHCOMMAREA ONLY if you are sure you have one available (EIBCALEN is not 0 and is equal to the expected size that you are working with), otherwise you will be causing storage violations in CICS which can endanger your entire CICS system !!!!!!!!!!! :!:

by **c62ap90** » Tue Nov 20, 2012 9:22 pm

mongan wrote:c62ap90 what you said is very dangerous . You can work with the DFHCOMMAREA ONLY if you are sure you have one available (EIBCALEN is not 0 and is equal to the expected size that you are working with), otherwise you will be causing storage violations in CICS which can endanger your entire CICS system !!!!!!!!!!!

Danger is my middle name!

Yep, I agree with you. I mention this since I see a fair amount of CICS programs referencing both the WS-COMMAREA and LS-(DFHCOMMAREA) field names interchangeably as if they are exactly the same data and most of the time it's "okay" but why risk, for example, a storage violation.

Do the "MOVE DFHCOMMAREA TO WS-COMMAREA." and reference WS- field names in your module.
Just remember to "MOVE WS-COMMAREA TO DFHCOMMAREA." on the way "out"/GOBACK.

Thanks.

by **mongan** » Fri Nov 23, 2012 9:10 pm

Again, that move back can be dangerous if the EIBCALEN is not correct, the safest method is to ALWAYS build your commarea from working-storage.

by **dstaudacher** » Tue Feb 26, 2013 7:45 am

" the safest method is to ALWAYS build your commarea from working-storage."

The best and safest way is to not have it in WORKING-STORAGE in the first place. Use this code, just after the PROCEDURE DIVISION statement in your top-level program:

IF EIBCALEN = 0
EXEC CICS GETMAIN SET (ADDRESS OF DFHCOMMAREA)
LENGTH (LENGTH OF DFHCOMMAREA) END-EXEC
END-IF

Now you have only ONE copy of the Commarea - always in Linkage - and you don't have to worry about moving it back and forth anymore or whether the correct and most current data is in Working Storage or Linkage. It's ALWAYS in Linkage.

IBM Mainframe Forum

DFHCOMMAREA

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Re: DFHCOMMAREA