Callable statement with RPG

Has anyone used a Callable statement that exec an RPG program that uses native 
I/O and return a result set.  We are passing a parm ID that reads a master file 
for all matching ID's, we then take the color code from the master file and 
read the color file for it's description, then the same with a size file and so 
on.  We want to return the compiled data as a resultset, but don't want to join 
5 tables.

Any ideas.

Thanks Barry