Scott, I was initially trying to use a service program function that, by defitnition, must return only one "value" -- Since I needed more than one array, I had to return a single data structure that had multiple array data structures nested within it. To IWS, my return was a structure which expanded to multiple array structures, and there was no support for displaying the Count for the nested structures.
When I used the parameters approach, IWS saw those parameters that did not specify CONST as input/output, and for those that were dimensioned it allowed me to replace the default Counts with my integer variables.
In that initial success I was using a *PGM object with the parameters. I have been trying to set up a *srvpgm function that returns a data structure comprised of a small collection of fields (no arrays there), as well as in/out parms for returning the arrays. Not having any success there yet. Don't know what I'm missing. The PCML appears to be error-free, but IWS does not recognize the operation as one that can be selected in the "Select Export Procedures to Externalize as a Web Service - Step 4 of 9".
I might be pushing my luck there, and may have to go back to the *PGM approach (because it works.)