prepro-ims-cobol.pl converts all EXEC DLI statements in input_file to CBLTDLI statements and prints all lines to stdout which can be redirected to a new file. After that the new file could be compiled with COBOL compiler. The environment variable COBCPY, which indicates to the Micro Focus COBOL compiler or COBOL-IT compiler where copybooks are stored, must be correctly set to include the IMS copybook path at $IMS_RT/cpylib during compilation time.

The preprocessor expects the input COBOL program to have a 6-column left-margin. The output is in fixed format, or an error message should appear.