MVS 3.8j From a Business Programmer Perspective

Install and Run MVS 3.8j

Your First PL/I Program

PL/I pronounced P L one, is a language developed by IBM in the mid 1960s. It was designed to be a mathmetical, scientifice, business, and systems programming language. It is still in use today and vendors other than IBM have compilers for it. If you plan on programming with it create a partitioned dataset named learn.pl1.src and create source membere named firstpgm. Let's look at a simple program.


          AVRG: PROC OPTIONS(MAIN);
            DECLARE LOANNAME CHAR(20);
            GET LIST(A,B,C,D,E,LOANNAME);
            SUM = A + B + C + D + E;
            MEAN = SUM /5;
            PUT LIST((10)' ' !! 'NAME IS: ' !! LOANNAME);
            PUT SKIP LIST('AVERAGE IS', MEAN);
            RETURN;
          END AVRG;

This statement reads from a file a list of variables. In this case it is reading five variable a, b, c, d, and e followed by reading a string variable. The GET statement has the ability to specify a dataset but this one doesn't which means by default is is reading from the dataset SYSIN.

Line #	Description
1	In PL/I programs are written as procedures. The name of this procedure is 'AVRG' and its options indicate that this is the MAIN procedure.
2	Variables are defined with the DECLARE keyword. This line defines a variable named LOANNAME that is alphanumeric and is 20 characters long.
3
4	This statement adds the five variable a, b, c, d, and e together and puts the result into a variable named sum.
5	This statement creates a variable 'mean' by dividing 'sum' by 5 (the number of variables added together.
6	This statement does a PUT to a dataset. If a dataset is not named it is written to SYSPRINT. The parameters for this put is 10 spaces concatenated with a string (quoted) concatenated with the variable 'LOANNAME'.
7	This statement does a PUT to the SYSPRINT dataset. It uses the keyword SKIP to indicate to advance one line then the parameters put out the word 'AVERAGE:', then it puts out the variable mean. Notice that is is not concatenated but there is a comma separating the two fields. This causes a number of spaces to be put between the two fields.
8	This statement says RETURN. It causes the program to terminate and return to the calling program.
9	This statement tells the compiler that this is the end of the procedure AVRG.

Note that every line is ended with a semi-colon (;).

Embedded Source
JCL Job Stream with embedded source


            //RLAWPL1 JOB  (PL1TEST),CLASS=A,MSGCLASS=H,MSGLEVEL=(1,1)
            //PL1TEST EXEC PL1LFCLG
            //PL1L.SYSLIN DD UNIT=SYSDA
            //PL1L.SYSIN  DD *
             AVRG: PROC OPTIONS(MAIN);
                DECLARE LOANNAME CHAR(20);
                GET LIST(A,B,C,D,E,LOANNAME);
                SUM = A + B + C + D + E;
                MEAN = SUM /5;
                PUT LIST((10)' ' !! 'NAME IS: ' !! LOANNAME);
                PUT SKIP LIST('AVERAGE IS', MEAN);
                RETURN;
             END AVRG;
            /*
            //LKED.SYSLIB DD DSN=SYS1.PL1LIB,DISP=SHR
            //GO.STEPLIB  DD DSN=SYS1.PL1LIB,DISP=SHR
            //GO.SYSIN    DD *
            45 20 60 30 70 'MY HOME LOAN'
            /*
            //

Notice the line GO.FT06F001, the 6 indicates that this is the DD line for device 6 in the program.

External Source
JCL Job Stream with external source


            //RLAWPL1 JOB  (PL1TEST),CLASS=A,MSGCLASS=H,MSGLEVEL=(1,1)
            //PL1TEST EXEC PL1LFCLG
            //PL1L.SYSLIN DD UNIT=SYSDA
            //PL1L.SYSIN  DD DSN=LEARN.PL1.SRC(FIRSTPGM)
            //LKED.SYSLIB DD DSN=SYS1.PL1LIB,DISP=SHR
            //GO.STEPLIB  DD DSN=SYS1.PL1LIB,DISP=SHR
            //GO.SYSIN    DD *
            45 20 60 30 70 'MY HOME LOAN'
            /*
            //