When there are more than 2 cases...

   IF CASE = 1
      PERFORM X
   END-IF
   IF CASE = 2
      PERFORM Y
   END-IF
   IF CASE = 3
      PERFORM Z
   END-IF


   IF CASE = 1
      PERFORM X
   ELSE 
      IF CASE = 2
         PERFORM Y
      ELSE 
         IF CASE = 3
            PERFORM Z
         ELSE
            PERFORM DEFAULT-ROUTINE
         END-IF
      END-IF
   END-IF


   IF CASE = 1
      PERFORM X
   ELSE IF CASE = 2
      PERFORM Y
   ELSE IF CASE = 3
      PERFORM Z
   ELSE
      PERFORM DEFAULT-ROUTINE
   END-IF

Using EVALUATE

   EVALUATE CASE
      WHEN 1
         PERFORM X
      WHEN 2
         PERFORM Y
      WHEN 3
         PERFORM Z
      WHEN OTHER
         PERFORM DEFAULT-ROUTINE
   END-EVALUATE