Error Handling for QCMDEXC

What's a good way to retrieve the full message or message data associated
with a failed call to QCMDEXC ?

In the code below at the point labeled ZZZ I would like to have access to
the full error message in effect at that time.  However, by definition, the
exception data in the program status data structure is only available when
the status is 9999.  In the code below, when commitment control is already
active before the call to this program, the new attempt to start commitment
control correctly generates a CPF8351 (commit control already active),
however it yields a status code = 00202 "Called program or procedure
failed".  So the exception data is blank (even though the PSDS has the
desired message ID of CPF8351).
        Thanks - Dave K.


C     *INZSR        BegSR

 *                  start commitment control
C                   eval      cmdStr = 'STRCMTCTL  LCKLVL *CHG'
C                   eval      cmdLen = %len( cmdStr )
C* the procedure 'command' is a prototyped call to QCMDEXC
C                   callp(e)  command(cmdStr : cmdLen)
C                   if        %error
C* CPF8351 indicates commitment control is already active
C                   if        psds_MsgID = 'CPF8351'
C                   rolbk
C                   else
C*    ZZZ    Friendly error handler goes here
C                   endif
C                   endif

note: the procedure "command" is defined as follows ...
D Command         PR                  ExtPgm('QCMDEXC')
D  CmdStr                    32702    const options(*varsize)
D  CmdLen                       15p 5 const

 * Program Status Data Structure
D psds          esds                  extname(PSDS) prefix(psds_)