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1993-01-19
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*******************************************
* *
* A STUDENT APPROACH TO *
* COBOL ON AN IBM MVS/XA OPERATING SYSTEM *
* *
*******************************************
John S. Ward
4/10/93
EJECT
In this handout we follow step-by-step instructions in creating
a COBOL program. Job Control Language (JCL) is used to demonstrate
file linkage as well as program execution. For the purpose of this
handout, we assume you have successfully accessed the ISPF/PDF
PRIMARY OPTION MENU shown below:
GEORGIA STATE UNIVERSITY COMPUTER CENTER
--------------------ISPF/PDF PRIMARY OPTION MENU-----------------------
OPTION ===>
USER ID -userid
0 ISPF PARAMS -Specify terminal and user parameters TIME -14:42
1 BROWSE -Display source data or output listing TERMINAL -3278
2 EDIT -Create or change source data PF KEYS -24
3 UTILITIES -Perform utility functions
4 FOREGROUND -Invoke language procedures in foreground
5 BATCH -Submit job for language processing
6 COMMAND -Enter TSO command or CLIST
7 DIALOG TEST -Perform dialog testing
8 LM UTILITIES-Perform library management utility functions
C CHANGE -Display summary of changes for this release
T TUTORIAL -Display information about ISPF/PDF
X EXIT -Terminate ISPF using log and list defaults
Enter END command or PF3 to terminate ISPF.
SECTION ONE: Creating your COBOL program.
1.1) Enter 6 at the "OPTION ===>" prompt of the ISPF/PDF PRIMARY OPTION
MENU, and hit return to go to TSO COMMAND PROCESSOR panel.
1.2) Type CREATE at the cursor, and hit return. Next, type your initial
when you are asked to "ENTER LIBRARY/APPLICATION NAME ===>". Hit
return, and type COBOL at the next prompt. Hit return one more
time when you see three asterisks displayed (hit return anytime
you see *** displayed).
1.3) Use the F4 key to go back to the primary menu. Then, enter 2 at
the "OPTION ===>" prompt to go to the EDIT - ENTRY PANEL.
Fill the sections of this panel as shown below:
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------------------------- EDIT - ENTRY PANEL ---------------------------
COMMAND ===>
ISPF LIBRARY:
PROJECT ===> your userid
GROUP ===> your initials ===> ===> ===>
TYPE ===> COBOL
MEMBER ===> program name (Blank for member selection list)
OTHER PARTITIONED OR SEQUENTIAL DATA SET:
DATA SET NAME ===>
VOLUME SERIAL ===> (If not catalogued)
DATA SET PASSWORD ===> (If password protected)
PROFILE NAME ===> (Blank defaults to data set type)
Hit return and you will see an empty file as shown below:
EDIT --- User-id.Initial.COBOL(member) ------------- COLUMNS 001 072
COMMAND ===> SCROLL ===>PAGE
****** *********************** TOP OF DATA **************************
''''''
''''''
''''''
''''''
''''''
''''''
.
.
Type UNNUM at the cursor and hit return. Press the TAB key twice,
type the letter "I" (insert), and hit return. Tab back then type
COLS and press return. Use the right arrow key to move the cursor
to the right. The first line of the body of a COBOL program will
start in column 8. The first line in the body of the COBOL program
will be the IDENTIFICATION DIVISION.
EDIT --- User-id.Initial.COBOL(member) ------------- COLUMNS 001 072
COMMAND ===> SCROLL ===>PAGE
****** ********************** TOP OF DATA ***************************
=COLS>----+----1----+----2----+----3----+----4----+----5----+----6----+
''''''
****** *********************BOTTOM OF DATA **************************
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Press return followed by the HOME key. This will take your cursor
back to the COMMAND line. Type the command RES which stands for
RESEQUENCE. This will cause the rulers to disappear.
Upon entering successive lines of text, the cursor will be placed
under the first non blank character of the previous line. Since
many of the lines of COBOL start in either column 8 or 12, this
is most convenient. You don't need to use the cursor keys or
space key near as much when entering successive lines of text.
After typing your program you should press the home key and type
the word SAVE on the COMMAND line. You may type CANCEL on the COMMAND
line to leave the EDIT screen without saving your program or changes
that you made to an existing program.
In writing the File Description (FD) sections of your COBOL
program, there are certain conventions that must be followed
when interfacing with the IBM operating system. The FD phrase
'BLOCK CONTAINS 0 CHARACTERS' allows record and block size to be
controlled by the Dataset Definition (DD) statements in the
JCL rather than the COBOL program.
Use the example below to help you with your own program.
EDIT --- user-is.init.COBOL(TEST1) - 01.01 --------- COLUMNS 001 072
COMMAND ===> SCROLL ===>PAGE
****** ******************** TOP OF DATA **************************
000001 //STEP1 EXEC COBUCLG
000002 IDENTIFICATION DIVISION.
000003 PROGRAM-ID. JOE-PROGRAMMER.
000004 DATE-COMPILED. JANUARY 5, 1993. 000005 ENVIRONMENT DIVISION.
000006 CONFIGURATION SECTION.
000007 SOURCE-COMPUTER. IBM-370.
000008 OBJECT-COMPUTER. IBM-370.
000009 INPUT-OUTPUT SECTION.
000010 FILE-CONTROL.
000011 SELECT INFILE ASSIGN TO UT-S-OLD.
000012 SELECT OUTFILE ASSIGN TO UT-S-NEW.
000013 DATA DIVISION.
000014 FILE SECTION.
000015 FD INFILE
000016 LABEL RECORDS ARE STANDARD
000017 BLOCK CONTAINS 0 CHARACTERS
000018 RECORD CONTAINS 56 CHARACTERS
000019 DATA RECORD IS INFILE.
000020 01 INFILE-COMPONENT.
000021 02 NAME PIC X(20).
000022 02 ACCT-NO PIC X(5).
000023 02 SSN PIC X(11).
000024 02 FILLER PIC X(20).
000025 FD OUTFILE
000026 LABEL RECORDS ARE STANDARD
000027 BLOCK CONTAINS 0 CHARACTERS
000028 RECORD CONTAINS 36 CHARACTERS
000029 DATA RECORD IS OUTFILE.
000030 01 OUTFILE-COMPONENT.
000031 02 NAME PIC X(20).
000032 02 ACCT-NO PIC X(5).
000033 02 SSN PIC X(11).
000034 WORKING-STORAGE SECTION.
000035 77 INFILE-STATUS PIC X(2).
000036 88 END-OF-FILE VALUE "10".
000037 PROCEDURE DIVISION.
000038 0000-MAIN.
000039 PERFORM 0010-INITIALIZE.
000040 PERFORM 0020-PROCESS-ONE-ACCOUNT UNTIL
000041 END-OF-FILE.
000042 PERFORM 0030-CLOSE.
000043 STOP RUN.
000044 0010-INITIALIZE.
000045 OPEN INPUT INFILE.
000046 OPEN OUTPUT OUTFILE.
000047 READ INFILE RECORD
000048 AT END MOVE "10" TO INFILE-STATUS.
000049 0020-PROCESS-ONE-ACCOUNT.
000050 MOVE CORR INFILE-COMPONENT TO
000051 OUTFILE-COMPONENT.
000052 WRITE OUTFILE-COMPONENT.
000053 READ INFILE RECORD
000054 AT END MOVE "10" TO INFILE-STATUS.
000055 0030-CLOSE.
000056 CLOSE INFILE.
000057 CLOSE OUTFILE.
000058 //GO.OLD DD DSN=userid.init.INDATA,DISP=SHR,
000059 // DCB=(BLKSIZE=56,RECFM=FB)
000060 //GO.NEW DD DSN=userid.init.OUTDATA,DISP=OLD,
000061 // DCB=(BLKSIZE=36,RECFM=FB)
****** ********************** BOTTOM OF DATA **************************
EJECT
In the example above, the lines that contain "//" in
columns one and two, are the JCL statements. JCL statements
perform the operations necessary to compile, link and execute
your program.
Notice that STEP1 executes a JCL procedure called COBUCLG.
This procedure will compile, link, and execute a COBOL program.
Within this procedure there are two steps called LNK and GO.
JCL Dataset Definitions and library references may be inserted
into the procedure by prefixing them with the step name followed
by a period. The LNK step contains all the JCL necessary to
to form an executable load module. The GO step contains all the
JCL necessary in linking input and output data files.
In the example above, GO.OLD tells the operating system that the
internal link name OLD to which the logical file INFILE was
assigned using the SELECT statement under the FILE-CONTROL section
of the program is to be referenced to the Data Set Name (DSN) or
the actual input file that you already created on disk.
GO.NEW references the internal link name NEW to which OUTFILE
was assigned by the SELECT statement under the FILE-CONTROL section.
The Disposition of the file informs the operating system whether or
not the file currently exists. The input file has a file disposition
equal to SHR (DISP=SHR). The output file has a file disposition equal
to OLD (DISP=OLD). This means that we have to create the input and
output files before we execute our program.
SECTION TWO: Creating your data files.
2.1) Type =3.2 at the "COMMAND ===>" prompt to go to the next panel.
Use the TAB key to tab to the "TYPE ===>" prompt. Enter the name
of your input file. Press the HOME key and enter "A" (for
allocation) and press return. another panel will be displayed
as the one shown below. Use these same parameters as input
to your panel.
------------------------ ALLOCATE NEW DATA SET -------------------------
COMMAND ===>
DATA SET NAME: User-id.Initial.Type
VOLUME SERIAL ===> (Blank for authorized default volume)
SPACE UNITS ===>TRKS (BLKS, TRKS or CYLS)
PRIMARY QUAN ===>1 (in above units)
SECONDARY QUAN ===>1 (in above units)
DIRECTORY BLOCKS===>0 (zero for sequential data set)
RECORD FORMAT ===>FB
RECORD LENGTH ===>56 << Sum of the pictures for this file >>
BLOCK SIZE ===>56 << Sum of the pictures for this file >>
For the RECORD LENGTH and BLOCK SIZE sections, enter the same
number you used in the RECORD CONTAINS clause of this file.
Then hit return to go back to the DATA SET UTILITY panel. Tab
to the "TYPE ===>" prompt and enter the name of your output file.
2.2) Create your output file the same way you created your input file.
EJECT
SECTION THREE: Filling in your data.
3.1) Type =2 at the "OPTION ===>" prompt to go to EDIT panel. Enter
the name of your input file. The file name should be entered
at the "TYPE ===>" prompt. This name has to be the same
as the one used in the DSN parameter of your input file. Now,
press return to enter your input data.
3.2) Press the return key. Your screen should now have two rows of
asterisks. Move you cursor to the first asterisk on the first
line and type the letter I. After pressing return you will
subsequently be prompted for each line of data. If no data
is entered prompting will stop. You may then move your cursor
to a line number while typing the letter I in order to resume
prompting.
3.3) When you are finished creating your input file, go back to the
EDIT - ENTRY PANEL by typing =2. At the "COMMAND ===>" prompt,
type the name of your output file (this name should be the same
one used in the DSN parameter).
Next, hit return, and type SAVE to save the empty output file.
SECTION FOUR: Executing your COBOL program.
4.1) To execute your program, enter =2 at the "COMMAND ===>" prompt.
Hit return to go to the EDIT - ENTRY PANEL.
4.2) Enter the word COBOL at the "TYPE ===>" prompt of this panel.
Then, enter the name of your COBOL program at the "MEMBER ===>"
prompt. Press return and your program will be displayed at
the terminal.
4.3) Enter the command 'SUBT A,10' at the "COMMAND ===>" prompt of
this panel and press return to submit your program to the system.
The "A" is the jobname character that will be suffixed to
your userid. The batch job is to use no more than 10 seconds
of central processing time.
EJECT
EDIT --- user-is.init.COBOL(TEST1) - 01.01 --------- COLUMNS 001 072
COMMAND ===> SUBT A,10 SCROLL ===>PAGE
****** ******************** TOP OF DATA **************************
000001 //STEP1 EXEC COBUCLG
000002 IDENTIFICATION DIVISION.
000003 PROGRAM-ID. JOE-PROGRAMMER.
000004 DATE-COMPILED. MAY 5, 1990.
000005 ENVIRONMENT DIVISION.
000006 CONFIGURATION SECTION.
000007 SOURCE-COMPUTER. IBM-370.
000008 OBJECT-COMPUTER. IBM-370.
000009 INPUT-OUTPUT SECTION.
000010 FILE-CONTROL.
.
.
.
.
000053 READ INFILE RECORD
000054 AT END MOVE "10" TO INFILE-STATUS.
000055 0030-CLOSE.
000056 CLOSE INFILE.
000057 CLOSE OUTFILE.
000058 //GO.OLD DD DSN=userid.init.INDATA,DISP=SHR,
000059 // DCB=(BLKSIZE=56,RECFM=FB)
000060 //GO.NEW DD DSN=userid.init.OUTDATA,DISP=OLD,
000061 // DCB=(BLKSIZE=36,RECFM=FB)
****** ********************** BOTTOM OF DATA **************************
Then, hit return, and you will see
IKJ56250I JOB useridA(JOBnumber) SUBMITTED
***
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SECTION FIVE: Accessing your job output.
5.1) At the "COMMAND ===>" prompt, type =o.h to go to the SDSF or System
Display and Search Facility PANEL H option.
_____________________________________________________________________________
|SDSF HELD OUTPUT DISPLAY ALL CLASSES 406 LINES LINE 1-1 (1)
|COMMAND INPUT ===> SCROLL ===> HALF
|NP JOBNAME TYPE JNUM #DSNS CRDATE C FCB DEST ROUTE #RECORDS RNUM RD-
| S USERIDA JOB 1139 5 8/15/91 X **** GSUMVS1 350 0275
|____________________________________________________________________________
5.2) Tab to the field under the NP heading and type in the letter
S to view you job output.
Below is a facsimile of a successful COBOL execution as viewed
from the SDSF menu option H.
BROWSE - USGHND.DAY.SPF235.OUTLIST ------------ LINE 000000 COL 001 080
COMMAND ===> SCROLL ===>HALF
********************************** TOP OF DATA ************************
1 J E S 2 J O B L O G -- S Y S T E M G S U 1 -- N O
0
11.12.36 JOB 2185 ICH70001I USGHND LAST ACCESS AT 11:09:25 ON TUESDAY, OC
11.12.36 JOB 2185 $HASP373 USGHNDX STARTED - INIT A - CLASS A - SYS GSU1
11.12.45 JOB 2185 - --TIMING
(
11.12.45 JOB 2185 -JOBNAME STEPNAME PROCSTEP RC EXCP CONN CPU
11.12.45 JOB 2185 -USGHNDX COB 00 332 1851 .00
11.12.45 JOB 2185 -USGHNDX LKED 00 332 1851 .00
11.12.45 JOB 2185 -USGHNDX GO 00 332 1851 .00
11.12.45 JOB 2185 -USGHNDX ENDED. NAME-USGHND /\ TOTAL CPU TIME=
11.12.46 JOB 2185 $HASP395 USGHNDX ENDED ]]
0------ JES2 JOB STATISTICS ------ ]]
- 18 OCT 88 JOB EXECUTION DATE ]]-------------------
- 9 CARDS READ ] A RETURN CODE (RC)
- 152 SYSOUT PRINT RECORDS ] OF ZERO MEANS YOUR
- 0 SYSOUT PUNCH RECORDS ] PROGRAM EXECUTED
- 8 SYSOUT SPOOL KBYTES ] WITHOUT ERRORS.
- 0.17 MINUTES EXECUTION TIME ]
1 //USGHNDX JOB I994998,USGHND, ]--------------------
// NOTIFY=USGHND,CLASS=A,MSGLEVEL=(1,1),
// USER=USGHND,TIME=(0,5)
5.3) To print your output file, type O under the NP heading. Your output
will normally be printed on one of the production laser printers
located on the ground floor of the Library South building. You can
change the destination by toggling to the field under the DEST header
and overlaying the GSUMVS1 destination. For example, if you want
your output printed on the high-speed printer located in LS109,
overlay the GSUMVS1 with TRM1.
See the SDSF handout for further information.
SECTION SIX: Logging off.
To logoff, enter =X at the "COMMAND ===>" or "OPTION ===>"
prompt of any panel. Once the operating system displays the
message READY, you may then type the command LOGOFF.
At this point you will be disconnected from the system.
IMPORTANT NOTE:
The program, input and output files that you have created are
saved in the system. Therefore subsequent executions should
reference sections 4.1 through 5.4.
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METHODS OF DEBUGGING
There are two popular ways to debug a COBOL program on the
MVS operating system.
METHOD #1:
If the program compiles with no syntax errors, but continues
to execute beyond the time allocated on the SUBT command, the
program may be in an infinite loop. In order to isolate the
looping pattern you may make use of the COBOL statement
READY TRACE. This command is always placed in column 12
of your program and is placed, just like any other COBOL
statement, within a paragraph. Upon execution of the program,
the name of each paragraph will be written to your SYSOUT.
With this information, you may be able to establish some sort
of looping pattern based on the names of the paragraphs.
The READY TRACE statement requires an additional line of JCL
in order to work. This statement should be typed at the bottom
of your program as follows:
//SYSOUT DD SYSOUT=*
METHOD #2:
If you want to take a peek at a given variable in your program,
you may do this using the COBOL DISPLAY statement. If you have
a variable named CNTR, you may look at the contents of this
variable using the DISPLAY statement. It might look as follows:
DISPLAY CNTR.
The DISPLAY statement also starts in column 12. The DISPLAY
statement also requires an additional line of JCL in order to
work. This statement should be typed at the bottom of your
program as follows:
//SYSOUT DD SYSOUT=*
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COMMONLY GENERATED ERROR MESSAGES
1) If you are getting a QSAM error message from the JCL, Job Control
Language, then check to make sure the following are correct:
A) Make sure the record size within your program matches the
record size of the file on disk.
B) Make sure the block size within your program matches the
block size of the file on disk.
C) Make sure that for every FD, File Description, there exist
a 'BLOCK CONTAINS 0 CHARACTERS'.
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COMMONLY USED FEATURES OF THE FILE EDITOR
ISPF/PDF
PROGRAM
FUNCTION KEYS NOTE: The more frequently used keys have
been marked with an asterisk
F1 HELP
F2 SPLIT SCREEN
* F3 END
F4 RETURN
F5 RFIND
F6 RCHANGE
* F7 UP SCREEN
* F8 DOWN SCREEN
F9 SWAP
* F10 LEFT SCREEN
* F11 RIGHT SCREEN
F12 CURSOR
------------------------------------------------------------------------
ISPF/PDF
MENUS
* =2 EDIT
=3.1 DELETE MEMBERS
=3.2 DELETE DATA SETS
=3.4 GET LISTING OF ALL DATA SETS
=3.6 GET PROGRAMS OF DATA FILES SENT TO PRINTER
* =X EXIT OR LOGOFF SYSTEM (then type: logoff)
------------------------------------------------------------------------
KEYBOARD NOTES
***** WHENEVER PROMPTED WITH '***' PRESS RETURN *****
***** IF PROMPTED WITH "READY" TO GET BACK ON THE *****
***** SYSTEM TYPE "ICF", OR IF YOU ARE FINISHED *****
***** TYPE "LOGOFF". *****
***** IF KEYBOARD FREEZES, PRESS THE TAB KEY *****
***** IF STILL FROZEN, PRESS THE return key *****
***** IF STILL FROZEN, PRESS CNTL G *****
***** IF KEYBOARD IS STILL LOCKED UP, PRESS ALT 2 *****
***** IF KEYBOARD IS STILL LOCKED UP, PRESS ALT 1 *****
------------------------------------------------------------------------
