Converting Packed to Char.

I want to create a procedure to return a varchar from a given number, len
and dec positions, like this:

eval MsgData = Filename + Filelib + CharNum(size: 7: 0)

I want to use CharNum() primarily to set the messagedata for my message
descriptions. Any ideas on how to accomplish this as elegantly as possible ?
My original thought is to create a DS like this:

D  NUM_P_0                1     15P 0
D  NUM_P_1                1     15P 1
D  NUM_P_2                1     15P 2
D  NUM_P_3                1     15P 3
D  NUM_P_4                1     15P 4
D  NUM_P_5                1     15P 5
D  NUM_P_6                1     15P 6
D  NUM_P_7                1     15P 7
D  NUM_P_8                1     15P 8
D  NUM_P_9                1     15P 9
D  CHARNUM                1     15A

and then according to the parameters passed as LEN & DEC assign the numeric
value to the corresponding field and return the data as a substr of CHARNUM.
I know it will work, but I really dont like this approach, any ideas would
be greatly appreciated.

Thanks in advance,

Carlos Kozuszko.