It should be an indexed file with the lock mode set to manual:

       SELECT LOCK-FILE
          ASSIGN TO RANDOM SYLCKFIL-PATH
          ORGANIZATION IS INDEXED
          ACCESS MODE IS DYNAMIC
          LOCK MODE IS MANUAL
          RECORD KEY IS LOCK-KEY
          FILE STATUS IS LOCK-FILE-STATUS.

The declarative should be coded like the following example so the application code can intercept a lock condition and give the user the appropriate error message:

       LOCK-FILE-ERROR SECTION.
          USE AFTER STANDARD ERROR PROCEDURE ON
              LOCK-FILE.

Notice that there is no error procedure.

To lock the file exclusively, the file should be opened I-O with lock. This is the same as using LOCK MODE IS EXCLUSIVE in the Select statement.

       OPEN-LOCK-FILE-WITH-LOCK.

          PERFORM GET-PATH.
          MOVE PASSING-DATA-PATH TO SYLCKFIL-PATH.
          OPEN I-O LOCK-FILE WITH LOCK.

The file naming convention must be ??LCK??? and the length of the record must be 24 bytes for the file handler to recognize that a lock file is being processed.

CLS