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Saturday, June 19, 2010




Match Merge logic is extensively used in COBOL programs to compare the data in two sequential files effectively. Only pre-requisite to for using this logic is, all input files to be in Sorted Order


Problem : I have 2 Sequential files File1  and File2.

                 If Record exists in both the files then write data into FILEA             

                 If Record exists only in File1 and not in File2 then write data into FILEB

                 If Record exists only in File2 and not in File1 then write data into FILEC


Solution: The effective way of solving above problem is, by using Match Merge Logic. Only pre-requisite to for using this logic is, all input files to be in Sorted Order.  First step sort I/P file


Explanation of Logic : Below listed are I/P and Output files data for say RollNo


File1                  File2                         FILEA                     FILEB                              FILEC

10                      10                               10                                

20                      20                               20

30                      50                                                               30

50                      60                               50                                                                     60

70                      99                                                                70

90                                                                                          90                                    99


         Open FILE1 and 2 in input mode, FileA, B, C in output mode

1.    Read File1     (Reads the record 10 )

2.    Read File2     (Reads the record 10 )


3.    Compare the Key Record of both Files  (File1-Rno = File 2-Rno).

a.      10 = 10; means record exists in both files)

b.    Write the  record in   FILE A


c.      As we need to advance further, repeat Step1  thru Step3


4.    When system reads the records  30 and 50, Step3 will Fail. So evaluate Step4

a.      If File1-Rno < File 2-Rno   (30 < 50)

b.      Record   30, which is > 20 and <50, means Rollno 30 is not present in FILE 2

c.      i.e., Record 30 exists only in File1

d.      Write the record into FILE B

e.      Now Read only FILE 1, and repeat thru step 3


5.    When system reads the records  70 and 60 from file1 and 2 respectively,  Step3,4 will Fail. So evaluate Step5

a.      If File1-Rno >  File 2-Rno   (70 > 50)

b.      Record  60 of file2, which is > 50 and <70, means Roll no 60 is not present in FILE 1

c.      i.e., Record 60 exists only in File2

d.      Write the record into FILE C

e.      Now Read only FILE 2, and repeat thru step 3


6.    Repeat above steps until end of both the files.

      Close all files


Advantages :  Open/close both file only once.




1.    Where do we use TSQs 

                Data in TSQ is stored as VSAM files

a.    Pageup and Pagedown Logic

b.    For writing Log Details (as we cant use Displays in CICS)


2.    How do we access the TSQ using a Key field

a.    Using RIDFIELD


3.    What is Sync Point and why is called as 2 Phase Commit

a.    Sync point is issued to save the data till that LUW.

b.    This is called as 2 Phase commit as , first it saves the data pertaining to File, Db2 then CICS data.

4.    I would like to generate only Input field (along with A, F, L) and not Output files in my Symbolic Map, how to achieve this ?

a.    Use Mode = IN   , in BMS macro

5.    How do you position your cursor on Map.

a.    Code   IC, in Attribute field of BMS macro of respective field

b.    Move -1 to Length field of respective field

c.    Using SEND MAP    CURSOR ( 100 )

6.    How do you test Physical Map layout in CICS region.

a.    Use CECI send Map () Mapset()

7.    What’s the debugging tool used for CICS

a.    We use CEDF/Intertest/Expeditor.

8.    How do you test / check the Cobol flow thru CEDF

a.    Use the Option TRACE

9.    How do Read a Vsam file  from Bottom to Top

a.    Move HIGH-VALUES to WS-KEY  and read previous

10.                       How do you execute Even steps in a job. Eg . execute only step2 in below example

//job1    job   ACC, Class=a,




    1. We can use the utility IEBEDIT or Use COND parameter. To skip first step use COND=ONLY, (this will flush the step1)