Is your stored procedure fenced or unfenced ? If not fenced, then the instance owner must have access to the path/file
If fenced, do you have a fenced userid? Your DBA should be able to tell this ..
To identify the fenced-id, either of the following ways will help:
a) If you have access, check for the contents of the file <instance home dir>/ctrl/.fencedID
b)
db2_ps | grep -i db2fmp
The owner of this this processes is the fenced id
The fenced id must have access to the path in question.
HTH
Sathyaram