When I was first learning about subprocedures I wrote one to deal with 
record locks. It will pop up a screen and tell the user who has a lock 
on the file. If the status code is not 01218 it pops up a different 
screen to tell the user that an unknown error has occurred and to contact 
the IT department.


Here are the programs and screens. Bear in mind that I wrote this about
five years ago. I am sure that there are at least a half dozen ways that
this code could be improved upon. ;-)

In your main program set up the SDS like so:
      ****************************************************************  
      * SYSTEM STATUS DATA STRUCTURE.                                *  
      ****************************************************************  
     D                SDS                                               
     D  STSERRMSG             91    170                                 


Use the (E) extender on the opcode. If an error is found, execute the
subroutine to determine the type of error and display the appropriate
screen.

     C                   READ(E)   file                          
      **************************************************************** 
      *  PROCESS RECORD LOCK.                                        * 
      **************************************************************** 
     C                   IF        %ERROR                              
     C                   EXSR      CHECK4LOCK                          


      ***************************************************************   
      * SUBROUTINE TO PROCESS RECORD LOCKS.                         *   
      ***************************************************************   
     C     CHECK4LOCK    BEGSR                                          
                                                                   
     C                   IF        %STATUS = 01218                      
     C                   CALLP     RCDLOCKR(STSERRMSG)                  
     C                   ELSE                                           
     C                   CALLP     UNKNOWNERR                           
     C                   ENDIF                                          
                                                                   
     C                   ENDSR                                          

Terry Anderson