This program basically just copies an input file to an output file. It makes no changes to the file. It does not print anything out or display anything.

Here are some other types of programs that fall into the same logic pattern:

1 a program that simply counts the records in a file

2 a program that copies all the records in a file but has different record descriptions on the input file and output file. That would make this a copy and reformat program

3 a program that copies all the records in one type of file, such as a VSAM file, and writes them out to another type of file, such as an ordinary sequential file

Here is a short explanation of some of the logic of SEQSIMP1. The logic shown in this program is the kind used in many companies and has become an industry standard.

It starts with the simple PERFORM INITIALIZATION, PERFORM PROCESS-ALL until the end of the file, PERFORM TERMINATION, followed by a GOBACK to end the program.

INITIALIZATION is for those things that are done once at the beginning of the program. PROCESS-ALL is the main controlling loop which does most of the work. TERMINATION is for those things done once at the end of the program.

PROCESS-ALL ends with an unconditional READ - so that READ will be done no matter what happens in PROCESS-ALL. If this READ is skipped for any reason, the program will loop without end. The first part of PROCESS-ALL does the bulk of the program’s work. It typically formats output lines and them writes them. Major logic decisions are normally done there, although this program has none.

Here is the program SEQSIMP1:

000200 IDENTIFICATION DIVISION.

000300 PROGRAM-ID. SEQSIMP1.

000400* This program just reads an input file and

000500* writes every record to the output file

000600* this is actually a copy program

000700* put many comments here -

000800* explain the program, inputs, outputs

000900* author, date, etc.

001000 ENVIRONMENT DIVISION.

001100 CONFIGURATION SECTION.

001200 INPUT-OUTPUT SECTION.

001300 FILE-CONTROL.

001400* INPUT FILE: PARTS

001500 SELECT IN-FILE ASSIGN PARTS.

001800* OUTPUT FILE: SEND TO PRINTER

001900 SELECT OUT-FILE ASSIGN OUTFILE.

002200 DATA DIVISION.

002300 FILE SECTION.

002400 FD IN-FILE

002410 RECORDING MODE IS F

002700 RECORD CONTAINS 80 CHARACTERS.

003000 01 IN-RECORD.

003010* PICTURES MUST CORRESPOND TO THE ACTUAL INPUT FILE

003020 05 PART-NUMBER PIC X(6).

003040 05 filler pic x.

003050 05 PART-DESC PIC X(30).

003060 05 filler pic x.

003070 05 QTY-ON-HAND PIC 9(3).

003080 05 filler pic x.

003090 05 QTY-ON-ORDER PIC 9(3).

003100 05 filler pic x.

003110 05 QTY-ON-RESERVE PIC 9(3).

003120 05 filler pic x.

003130 05 PART-PRICE PIC 9(3)V99.

003130 05 UNUSED PIC X(25).

003140

003200 FD OUT-FILE

003210 RECORDING MODE IS F

003600 RECORD CONTAINS 80 CHARACTERS.

003700 01 OUT-RECORD PIC X(80).

003800

003900 WORKING-STORAGE SECTION.

004000 01 SWITCHES.

004100 05 FILE-AT-END PIC X VALUE 'N'.

004200

004300 01 RECORD-COUNT PIC S9(7) PACKED-DECIMAL VALUE +0.

004400 01 DISPLAY-RECORD-COUNT PIC Z(6)9.

006000

006100 01 WS-OUT-RECORD.

006200 05 OUT-PART-NUMBER PIC X(6).

006300 05 filler pic x.

006400 05 OUT-PART-DESC PIC X(30).

006500 05 filler pic x.

006600 05 OUT-QTY-ON-HAND PIC 9(3).

006700 05 filler pic x.

006800 05 OUT-QTY-ON-ORDER PIC 9(3).

006900 05 filler pic x.

007000 05 OUT-QTY-ON-RESERVE PIC 9(3).

007100 05 filler pic x.

007200 05 OUT-PART-PRICE PIC 9(3)V99.

007300 05 OUT-UNUSED PIC X(25).

007400

007500 PROCEDURE DIVISION.

007600** Please keep the first part of your program simple

007700** perform beginning, perform main loop til no more records,

007800** perform the end

007900** please note the style of using periods

008000** only before and after paragraph names

008100** and at physical end of program.

008200 PERFORM INITIALIZATION

008300 PERFORM PROCESS-ALL

008400** UPPER CASE Y, PLEASE

008500 UNTIL FILE-AT-END = 'Y'

008600 PERFORM TERMINATION

008700 GOBACK.

008800

008900 INITIALIZATION.

009000* In this part you do the things you need to do once only

009100* at the beginning of the program

009200* please read the first record! This logic depends on it

009300 OPEN INPUT IN-FILE

009400 OUTPUT OUT-FILE

009500 PERFORM READ-PAR.

009600

009700 PROCESS-ALL.

009800* This is performed once for each record read

009900* it is the most important part of the program

010000* you generally do three things:

010100* process input record and/ or format output record

010200* write the output record

010300* read next input record (don't forget this)

010400* formatting the output record:

010500* in a simple program like this you could move

010600* the whole record instead of the individual fields

010700* as shown here

010800 MOVE PART-NUMBER TO OUT-PART-NUMBER

010900 MOVE PART-DESC TO OUT-PART-DESC

011000 MOVE QTY-ON-HAND TO OUT-QTY-ON-HAND

011100 MOVE QTY-ON-ORDER TO OUT-QTY-ON-ORDER

011200 MOVE QTY-ON-RESERVE TO OUT-QTY-ON-RESERVE

011300 MOVE PART-PRICE TO OUT-PART-PRICE

011400 MOVE UNUSED TO OUT-UNUSED

011500* I have adopted the style of the write from

011600* there is very little controversy over this

011700* because it would be awkward to write different types of

011800* print lines if you didn't do a write from

011900* this will be more obvious in programs that do reports

012000 WRITE OUT-RECORD FROM WS-OUT-RECORD

012100 PERFORM READ-PAR.

012200

012300 TERMINATION.

012400* Here you do what you need to do once only

012500* after all records have been processed

012600* and you are ready to end

012700* this might include final totals, for example

012800* move record-count to display-record-count

012900* display puts the data item directly to the printer

013000* DISPLAY DISPLAY-RECORD-COUNT

013100 CLOSE IN-FILE OUT-FILE.

013200

013300 READ-PAR.

013600 READ IN-FILE

013700 AT END MOVE 'Y' TO FILE-AT-END

013800* I included the code to count input records

013900* although it is commented out

014000* not at end add 1 to record-count

014100 END-READ.

Here is the input data file PARTS: (the next two lines are a column ruler)

1 2 3 4 5 6

123456789.123456789.123456789.123456789.123456789.123456789.12345678

PART01 LEFT HANDED WIDGET WRENCHES 003 007 002 10022

PART02 LEAD-WINGED GLIDERS 004 006 001 14054

PART04 LEFT FOOT REEBOKS 021 002 004 04323

PART06 286 COMPUTERS W 4K HARD DISK 043 077 012 00042

Here is sample JCL:

//STEP1 EXEC PGM=SEQSIMP1

//STEPLIB DD DSN=your.executable.program.library.goes.here,DISP=SHR

//*OF COURSE, THE NEXT LIBRARY NAME MAY BE DIFFERENT AT YOUR COMPANY

//PARTS DD DSN=userid.CLASS.DATA(PARTS),DISP=SHR

//OUTFILE DD SYSOUT=*

//SYSOUT DD SYSOUT=*

//SYSUDUMP DD SYSOUT=*