What is the Input/Output FILE Identification section?
//INPUT1 DD DSN=INFILE,DISP=SHR
//OUTPUT DD SYSOUT=A
The fields INPUT1 and OUTPUT1 must correspond to the name following the ASSIGN TO statement in the FILE-CONTROL section of the COBOL Program.
FILE-CONTROL.
SELECT INPUT-FILE ASSIGN TO INPUT1.
SELECT OUTPUT-FILE ASSIGN TO OUTPUT1.
DD Field stands for Data Definition. Its main task is to tell the MVS OS, the input files from which data is read, and output file, to which OUTPUT information is written.
//INPUT1 DD DSN=INFILE,DISP=SHR
...DSN : A file containing records in IBM Mainframes is called Dataset. Every dataset has a name ; DataSetName(DSN).
DSN = INFILE indicates that the input data will be read from the Dataset INFILE.
SYSOUT=A indicates that the output will be written to the default printer(Job Spool).
DISP=SHR says that Disposition is Shareable. This means, that the dataset INFILE is not reserved for exclusive use. Other Jobs /Users can use this dataset simultaneously.
