Replacing subroutines with subprocedures

Please help a sub-procedure novice!

I currently have a program (call it 'MidPgm') that is
called by many other programs (call them 'TopPgm's).

MidPgm then executes subroutines whose names had
been specified and passed as parameters by 'TopPgm'.
These names are moved into an array (Subr) which is
Looped through and the subroutines are executed.
All these subroutines require the same type of input and
return data of the same format (a record, number, and a code).
 
This is accomplished by using 'when' statements.
For Idx = 1 to 5;
   Select;
        When Subr(Idx) = 'GetMax';
                Exsr GetMax;
        When Subr(Idx) = 'GetMin';
                Exsr GetMin;
        etc....
   EndSl;
EndFor;

Since these subroutines are also included in other 'mid' type
programs, I am hoping to replace them with external subprocedures
(call them 'BotPgm's).

I was hoping for a way to reduce coding lines and make this
procedure more 'reusable', if not generic, with something
along the following lines. 

TopPgm would pass subprocedure names instead of subroutine names.

MidPgm and BotPgms would include a '/copy' member containing a
'generic' prototype for the BotPgms with a 'variable' name, since all
the
subprocedures would have identical input and return parameters.

*********   PROBLEM AREA   **********
(Can't use ExtPgm with a procedure that returns a parameter)
(can't use 'character variable' as parameter for ExtProc)
(can't use 'character variable' as parameter for %PAddr)
(can't have this PR refer to more than 1 ExtProc)
D CalPgm        PR              LikeDs(OutPrmsDs)
                                ExtProc(VarName)
D  InPrms                       LikeDs(InPrmsDs)
(note: OutPrmsDs and InPrmsDs are also declared in the /copy member)

The 'For' loop would be changed to:

For Idx = 1 to 5;
   If Subr(Idx) <> *Blank;

*********   PROBLEM AREA   **********
        VarName = Subr(Idx);
        OutPrms = VarName(InPrms);
   EndIf;

Since I can resolve this in my head ( the program name (in VarNam) is
known,
It's tied it to the prototype 'CalPgm' for parameter resolution) I would
think there
would be a way to code this, but I AM STUCK. Any help would be
appreciated.

Tim Kredlo
(still confused, but not as much as I was a week ago)