CICS Sample Program, Explains How to use Link Command

Two sample programs given below. Those are main program and sub-program.

Link Command

1# Main Program

 ID DIVISION.
 PROGRAM-ID. HAS.
 DATA DIVISION.
 WORKING-STORAGE SECTION.
 77 TID PIC X(4).
 77 MSG PIC X(50) VALUE 'IMPORTANT OF LINK PROGRAM'.
 77 A PIC X(35) VALUE 'THIS IS MAIN PROGRAM'.
 77 B PIC X(35) VALUE 'NOW CONTROL MOVE TO SUB'.
 77 C PIC X(40) VALUE 'THANK U BYE'.
 PROCEDURE DIVISION.
 EXEC CICS RECEIVE INTO (TID)
 LENGTH(LENGTH OF TID)
 END-EXEC.
 EXEC CICS SEND
 FROM(MSG)
 END-EXEC.
 EXEC CICS RECEIVE END-EXEC.
 EXEC CICS SEND
 FROM(A)
 ERASE
 END-EXEC.
 EXEC CICS RECEIVE END-EXEC.
 EXEC CICS SEND FROM(B) END-EXEC.
 EXEC CICS RECEIVE END-EXEC.

EXEC CICS LINK
PROGRAM('SUB')
END-EXEC.
EXEC CICS SEND FROM(C) ERASE END-EXEC.
EXEC CICS RECEIVE END-EXEC.
EXEC CICS RETURN END-EXEC.

The logic for Sub program when you use LINK in main program.

#2 Sub Program for LINK

 ID DIVISION.
 PROGRAM-ID. SEN.
 DATA DIVISION.
 WORKING-STORAGE SECTION.
 77 D PIC X(35) VALUE 'THIS IS SUB PROGRAM'.
 77 E PIC X(50) VALUE 'NOW CONTROL TO MAIN'.
 PROCEDURE DIVISION.
 EXEC CICS SEND FROM(D) END-EXEC.
 EXEC CICS RECEIVE END-EXEC.
 EXEC CICS SEND FROM(E) END-EXEC.
 EXEC CICS RECEIVE END-EXEC.
 EXEC CICS RETURN END-EXEC.

#3 CICS Function Key(EIBAID)

 ID DIVISION.
 PROGRAM-ID. AD12GM.
 DATA DIVISION.
 WORKING-STORAGE SECTION.
 COPY ADD001.
 01 RES.
 02 A PIC 9(3).
 02 B PIC 9(3).
 02 C PIC 9(4).
 77 Z PIC X(80).
 PROCEDURE DIVISION.
 MOVE LOW-VALUES TO ADD1I.
 MOVE LOW-VALUES TO ADD1O.
 EXEC CICS
 SEND MAP('ADD1') MAPSET('ADD001')
 END-EXEC.
 MAIN-PARA.
 EXEC CICS HANDLE AID
 PF1(ADD-PARA)
 PF2(SUB-PARA)
 ANYKEY(E-PARA)
 END-EXEC.
 EXEC CICS
 RECEIVE MAP('ADD1') MAPSET('ADD001')
 END-EXEC.
 ADD-PARA.
 MOVE NO1I TO A.
 MOVE NO2I TO B.
 COMPUTE C = A + B.
 MOVE C TO RESO.
 MOVE 'ADD SUCCESSFUL' TO MSGO.
 EXEC CICS
 SEND MAP('ADD1') MAPSET('ADD001')
 ERASE
 END-EXEC.
 EXEC CICS RETURN END-EXEC.
 SUB-PARA.
 MOVE NO1I TO A.
 MOVE NO2I TO B.
 COMPUTE C = A - B.
 MOVE C TO RESO.
 MOVE 'SUB SUCCESSFUL' TO MSGO.
 EXEC CICS
 SEND MAP('ADD1') MAPSET('ADD001')
 ERASE
 END-EXEC.
 EXEC CICS RETURN END-EXEC.
 E-PARA.
 MOVE 'PRESS F1 AND F2' TO MSGO.
 EXEC CICS SEND
 SEND MAP('ADD1') MAPSET('ADD001')
 ERASE
 END-EXEC.
 go to main-para.

How to write a piece of code to add logic for function keys in CICS.

#4 ADD Program in CICS-COBOL

 PROGRAM-ID. AD12GM.
 DATA DIVISION.
 WORKING-STORAGE SECTION.
 COPY ADD001.
 01 RES.
 02 A PIC 9(3).
 02 B PIC 9(3).
 02 C PIC 9(4).
 77 Z PIC X(80).
 PROCEDURE DIVISION.
 MOVE LOW-VALUES TO ADD1I.
 MOVE LOW-VALUES TO ADD1O.
 EXEC CICS
 SEND MAP('ADD1') MAPSET('ADD001')
 END-EXEC.
 EXEC CICS
 RECEIVE MAP('ADD1') MAPSET('ADD001')
 END-EXEC.
 MOVE NO1I TO A.
 MOVE NO2I TO B.
 COMPUTE C = A + B.
 MOVE C TO RESO.
 EXEC CICS
 SEND MAP('ADD1') MAPSET('ADD001')
 ERASE
 END-EXEC.
 EXEC CICS RETURN END-EXEC.

5# Map for Addition

 DFHMSD TYPE=&SYSPARM,                                         X
 MODE=INOUT,                                                   X
 TIOAPFX=YES,                                                  X
 STORAGE=AUTO,                                                 X
 LANG=COBOL,                                                   X
 CTRL=FREEKB
 ADD01   DFHMDI SIZE=(24,80),LINE=1,COLUMN=1
 DFHMDF INITIAL='ADD    PGM',POS=(1,38),LENGTH=10,ATTRB=PROT
 DFHMDF INITIAL='ENTER NO1:',POS=(05,11),LENGTH=10,ATTRB=PROT
 NO1        DFHMDF POS=(05,22),LENGTH=3,ATTRB=(UNPROT,IC),PICIN='999',         X
 INITIAL=''
 DFHMDF POS=(05,26),LENGTH=1,ATTRB=ASKIP
 DFHMDF INITIAL='ENTER NO2:',POS=(06,11),LENGTH=10,
ATTRB=ASKIP
 NO2       
DFHMDF POS=(06,22),LENGTH=03,ATTRB=UNPROT,PICIN='999',              X
 INITIAL=''
 DFHMDF INITIAL='RESULT  :',POS=(08,11),                        X
 LENGTH=09,ATTRB=PROT
 RES       DFHMDF POS=(08,22),ATTRB=UNPROT,                                    X
 LENGTH=04,PICOUT='9999',                                       X
 INITIAL='____'

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