CICS Input Processing

A pseudo-conversational CICS program sends a map, ends, and runs again when the user presses a key. The second run reads the screen with RECEIVE MAP, looks at EIBAID to see which key was pressed, checks the fields, and either updates a file or sends the map again with a message. The task does not sit in memory while the user reads the screen.

Receive the map

RECEIVE MAP names the map and the mapset that built the screen. INTO names the symbolic map area generated from the BMS map. RESP keeps the condition in your working storage so you can branch without a HANDLE CONDITION you forgot to pop.

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           EXEC CICS RECEIVE
                MAP('PAYMAP')
                MAPSET('PAYSET')
                INTO(PAYMAPI)
                RESP(WS-RESP)
           END-EXEC.
 
           IF WS-RESP NOT = DFHRESP(NORMAL)
               PERFORM SEND-MAPFAIL
               EXEC CICS RETURN END-EXEC
           END-IF.

Which key

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           EVALUATE EIBAID
               WHEN DFHPF3
                   EXEC CICS RETURN END-EXEC
               WHEN DFHENTER
                   PERFORM CHECK-FIELDS
               WHEN OTHER
                   MOVE 'USE ENTER OR PF3' TO MSGO
                   PERFORM SEND-MAP
           END-EVALUATE.

Check fields, then update

Symbolic input fields can be empty, low-values, or the wrong picture. Test them before READ UPDATE or REWRITE. Send the same map with the cursor on the bad field and a one-line message. A file update belongs on the path where RESP was NORMAL, EIBAID was Enter, and the fields passed the checks.

1. RECEIVE with RESP.
2. EVALUATE EIBAID.
3. Validate the symbolic fields.
4. Update, then SEND MAP and RETURN TRANSID(EIBTRNID).

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           EXEC CICS RETURN
                TRANSID(EIBTRNID)
                COMMAREA(WS-COMMAREA)
                LENGTH(WS-COMM-LEN)
           END-EXEC.

EIBTRNID is the transaction the user already typed, so the next Enter starts the same program. The commarea holds whatever the next task must remember. A waiting conversational RECEIVE holds a task and a thread for the whole think time. Return instead.

Explain it like I'm five

You slide a form across the counter and walk away. When the person rings the bell (Enter), you come back, read the form, and either fix a box they left blank or file the form. You do not stand at the counter while they hunt for a pen.

Exercises

1. Write RECEIVE MAP for PAYMAP in mapset PAYSET with RESP.
2. Branch on PF3 versus Enter.
3. List the checks you want on an account-number field before REWRITE.
4. Say why RETURN TRANSID beats a RECEIVE that waits on the terminal.

Quiz