Run-length encoding in COBOL

RLE.cbl

      *-----------------------
       IDENTIFICATION DIVISION.
      *-----------------------
       PROGRAM-ID.    RLE.
      *--------------------
       DATA DIVISION.
      *-------------
       WORKING-STORAGE SECTION.
       01 INSTR           PIC X(80).
       01 OUTSTR          PIC X(80).
       01 LASTCHR         PIC X.
       01 CHR             PIC X.
       01 CHRCOUNT        PIC 9(1).
       01 COUNTER         PIC 9(2).
      *------------------
       PROCEDURE DIVISION.
      *------------------
       MAIN.
           MOVE Z'aaabbcaa' TO INSTR.
           PERFORM RUNLENGH-ENCODE.
           PERFORM DISP-RESULT.
           STOP RUN.

       DISP-RESULT.
           MOVE 0 TO COUNTER
           INSPECT OUTSTR TALLYING COUNTER FOR CHARACTERS BEFORE X'00'.
           DISPLAY OUTSTR(1:COUNTER).

       RUNLENGH-ENCODE.
           MOVE 1 TO CHRCOUNT.
           MOVE INSTR(1:1) TO CHR.
           MOVE INSTR(1:1) TO LASTCHR.
           MOVE Z'' TO OUTSTR.

           PERFORM VARYING COUNTER FROM 2 BY 1
             UNTIL CHR EQUAL X'00'

             MOVE INSTR(COUNTER:1) TO CHR

             IF CHR EQUAL LASTCHR AND CHRCOUNT < 9 THEN
               ADD 1 TO CHRCOUNT
             ELSE
               STRING
                 OUTSTR DELIMITED BY X'00'
                 CHRCOUNT DELIMITED BY SIZE 
                 LASTCHR DELIMITED BY SIZE
                 X'00' DELIMITED BY SIZE
                 INTO OUTSTR
               END-STRING

               MOVE 1 TO CHRCOUNT
               MOVE CHR TO LASTCHR
             END-IF
           END-PERFORM.

RLE.jcl

//RLEJ    JOB 1,NOTIFY=&SYSUID
//***************************************************/
//COBRUN  EXEC IGYWCL
//COBOL.SYSIN  DD DSN=&SYSUID..CBL(RLE),DISP=SHR
//LKED.SYSLMOD DD DSN=&SYSUID..LOAD(RLE),DISP=SHR
//***************************************************/
// IF RC = 0 THEN
//***************************************************/
//RUN     EXEC PGM=RLE
//STEPLIB   DD DSN=&SYSUID..LOAD,DISP=SHR
//SYSOUT    DD SYSOUT=*,OUTLIM=15000
//CEEDUMP   DD DUMMY
//SYSUDUMP  DD DUMMY
//***************************************************/
// ELSE
// ENDIF