Scenario - Join the below two files based on the student number.

Input File1 - MATEPK.SORT.INPUT01 - FB file of 80 length

----+----1----+----2---+---3---+---4----+---5---+----6---+---7---+---8
00001     student1           dept1
00003     student3           dept2
00004     student4           dept1
00005     student5           dept2
00002     student2           dept3
00006     student6           dept3
00008     student8           dept1
00007     student7           dept3
00009     student9           dept2
00010     student10          dept2

Input File2 - MATEPK.SORT.INPUT02 - FB file of 80 length

----+----1---+---2---+----3---+----4----+---5----+----6----+---7---+----8
          00001     560
          00003     520
          00004     540
          00005     500
          00002     510
          00006     550
          00008     530
          00007     510                                            
          00010     505

JCL -

---+----1----+----2---+---3---+----4---+----5---+
//MATEPKD  JOB (123),'MTH',NOTIFY=&SYSUID
//*
//STEP01   EXEC PGM=SORT
//IN1      DD DSN=MATEPK.SORT.INPUT01,DISP=SHR
//IN2      DD DSN=MATEPK.SORT.INPUT02,DISP=SHR
//SORTOUT  DD DSN=MATEPK.SORT.OUTPT01,
//             SPACE=(CYL,(1,1),RLSE),DCB=*.IN1,
//             DISP=(NEW,CATLG,DELETE)
//SYSOUT   DD SYSOUT=*
//SYSIN    DD *
     OPTION COPY
     JOINKEYS F1=IN1,FIELDS=(1,5,A)
     JOINKEYS F2=IN2,FIELDS=(11,5,A)
     REFORMAT FIELDS=(F1:1,40,F2:21,3)
/*

Output File - MATEPK.SORT.OUTPT02 - FB file of length 80

----+----1----+----2----+---3---+---4---+---5----+---6---+---7----+----8
00001     student1           dept1      560
00002     student2           dept3      510 
00003     student3           dept2      520
00004     student4           dept1      540
00005     student5           dept2      500
00006     student6           dept3      550
00007     student7           dept3      510
00008     student8           dept1      530
00009     student9           dept2      520
00010     student10          dept2      505

Explaining Example -

1. JOINKEYS F1=IN1,FIELDS=(1,5,A) - Specifies the file1 join criteria.
2. JOINKEYS F2=IN2,FIELDS=(11,5,A) - Specifies the file2 join criteria.
3. REFORMAT FIELDS=(F1:1,40,F2:21,3) - Reformat the output record with both files data by specifying starting and ending position.

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