SORT in COBOL

External Sort is used to sort the file externally, like through JCL.

Internal sort is used to sort the file inside COBOL program using SORT verb.

Three files are used in the sort process in COBOL:

Input file – The file which needs to be sorted either in ascending or descending order.

Work file – The file which is used to hold the records during sort process. Input file records are transferred to this file for the sorting process. This file needs to be defined in File section under SD entry.

Output file – Final file which contains the records in the desired sorted order.

Syntax: 

SORT work-file ON ASCENDING-KEY/DESCENDING-KEY

      USING input-file GIVING output-file

Once the sorted records are moved to output file, the sort file will be deleted.

//INFILE DD DSN=input-file

//OUTFILE DD DSN=output-file

//SORTWK DD DSN=&&TEMP

Work file should be opened in I-O mode.