Additional Error Specs from C-Proc. 'system'

Hi,
I use the above C-Procedure for execution of OS/400-Commands as a substitute
to QCMDEXC.
This procedure returns an error message ID by an IMPORT function.
My code, I have copied from somewhere, looks like:

D RunCmdC         PR            10I 0 ExtProc('system')
D  p$CmdStg                            *   Value Options(*string)
D yMsgIDImp       S                7A   Import('_EXCP_MSGID')
D yOK                 C                     0
   if   RunCmdC(p$CmdStg) <> yOK;
   $ErrMsg=yMsgIdImp;
   endif;

In case of an error I just can get back the message ID.
As I'm not familar with the C language I wonder if (and how) it would be
possible to get back more error message informations (e.g. message data,
message text, message file, message file library) in this procedure.

Many thanks for any ideas.
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