Question

I am writing a CL program which is going to encounter a lot of errors, due to the fact that it will be executed in environments with all sorts of problems like missing objects (yes, that is deliberate). Instead of monitoring these possible messages and bypass the errors, I actually would like to redirect these messages so that they can be used the program messages and displayed to the user. So what I want is that after the program execution, the program puts all the error messages onto display on the bottom of the screen rather than having them pop up and disrupt the execution. Is it possible to do so? How?

Answer 1

This is my standard CL error handling process. Generally, I would use MONMSG inline to handle errors I expect might be coming. Also generally, for errors I expect, I do not normally tell the end user about them. If you need to do that, make the RCVMSG/SNDPGMMSG pairs into a subroutine and call that inline to percolate the errors to the caller. The idea is to receive the diagnostic messages and re-send them to the caller, then do the same with the exception message.

    PGM

    DCL &MSGID  *CHAR 7    
    DCL &MSGDTA *CHAR 256 

    /* Trap all errors, and let the error routine handle */
    MONMSG (CPF0000 MCH0000) EXEC(GOTO ERROR)      

    /* processing happens here */
    /* if an unexpected error occurs, we drop to the error routine */

/* We expect this error, but tell the caller about it anyway */
dltf mylib/myfile
monmsg cpf2105 exec(do)
callsubr percolate
endoo

    /* end of processing */
    RETURN                                                    

            /* This is the error handling routine.  Basically it */       
            /* simply re-sends the messages back up to the       */       
            /* caller, so it dies "gracefully" instead of        */       
            /* giving a hard halt.                               */       
                           /* Re-send diagnostic messages */              
    ERROR:      RCVMSG     MSGTYPE(*DIAG) MSGDTA(&MSGDTA) MSGID(&MSGID)   
                IF         (&MSGID *EQ '       ') GOTO ERROR_ESC          
                SNDPGMMSG  MSGID(&MSGID) MSGF(QCPFMSG) MSGDTA(&MSGDTA) +  
                             MSGTYPE(*DIAG)                               
                MONMSG     (CPF0000 MCH0000)                              
                GOTO       ERROR                                          

                           /* Re-send escape message and RETURN */        
    ERROR_ESC:  RCVMSG     MSGTYPE(*EXCP) MSGDTA(&MSGDTA) MSGID(&MSGID)   
                SNDPGMMSG  MSGID(&MSGID) MSGF(QCPFMSG) MSGDTA(&MSGDTA) +  
                             MSGTYPE(*ESCAPE)                             
                MONMSG     (CPF0000 MCH0000)                              
                RETURN                                                    

                ENDPGM                                                    

EDIT: Add subfile message queue to answer.

Perhaps a subfile message queue?
DDS:

 A          R BMENUS                    SFL
 A*
 A                                      TEXT('Message subfile')
 A                                      SFLMSGRCD(20)
 A            WMSGK                     SFLMSGKEY
 A            WPGMQ                     SFLPGMQ
 A          R BMENUC                    SFLCTL(BMENUS)
 A*
 A                                      TEXT('Message subfile control recor-
 A                                      d')
 A                                      OVERLAY
 A                                      LOCK
 A                                      SFLDSP
 A                                      SFLINZ
 A                                      SFLSIZ(0006)
 A                                      SFLPAG(0003)
 A            WPGMQ                     SFLPGMQ

CLP:

         DCLF       FILE(BMENUFM)
         ...
         CHGVAR     &WPGMQ 'BMENU'
         ...
         SNDF       RCDFMT(BMENUC)
         SNDRCVF    RCDFMT(BMENUR)