More Efficient Processing ideas...

Currently my program below reads every single record in the file to see if it 
matches certain criteria before processing a record.  There are millions
of records in this file and it takes the program forever to complete.  The 
criteria for checking each record depends on whatever the user enters.  So
far there's
about 5 or 6 criteria it must meet.  1 happens to be a date range, another is 
customer number, billing numbers, etc...  I don't want to create any
logicals since
the criteria can change, but I'd like to have the subprocedure read a file 
that's already sorted.

Would executing an OPNQRYF statement via QCMDEXC before executing the 
subprocedure be the best route?  SQL? other ideas?

     P FILE_PRCS        B
      *
      /FREE

           // Read FB File
           SETLL *LOVAL FILE_A;
           DOU %EOF(FILE_A);
           READ FILE_A;

                // End of File
                IF %EOF(FILE_A);
                LEAVE;
                ENDIF;

                // Validate Record
                IF BLAH BLAH = BLAH BLAH etc...;
                PROCESS_RECORD();
      ELSE;
      ITER;
      ENDIF;

            ENDDO;

      /END-FREE
      *
     P FILE_PRCS        E