CLP - coding qualified object references

How can I code a CLP to accept the two parameters Job Description and *JOBD
Library, such that when they are used as parameters on an embedded SBMJOB
command they are properly respected ?  The following test program works fine
with a named *JOBD and Library (Test#1 below).  However the program fails
when the special value *USRPRF is specified for the *JOBD (Test#2 below), no
matter how I  specify the *JOBD Library on the call.  -DaveK

/* CLLE or CLP source member named TEST, compiled as a program */
pgm (&JobD &JobDLib)
dcl &JobD       *char 10
dcl &JobDLib    *char 10

             ?          SBMJOB CMD(chgjob runpty(40)) JOB(testjob) +
                          JOBD(&jobdlib/&jobd)
                        MONMSG CPF6801  /* user pressed F12 to cancel */
endpgm
---------------------------------------------------------------------
TEST#1 - successful test with a named *JOBD and Library
call test (ABC XYZ)
                               Submit Job (SBMJOB) - partial display
Job description  . . . . . . . . > ABC           Name, *USRPRF
  Library  . . . . . . . . . . . >   XYZ         Name, *LIBL, *CURLIB
---------------------------------------------------------------------
TEST#2 - Note the error message at bottom
call test (*USRPRF ' ')
                               Submit Job (SBMJOB) - partial display
  Job description  . . . . . . . . > *USRPRF       Name, *USRPRF
   Library  . . . . . . . . . . . >   ' '         Name, *LIBL, *CURLIB
 Value '*USRPRF   ' for parameter JOBD not a valid name.
---------------------------------------------------------------------

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