Randy, are you referring to the RESLIST function of TSSAI? Default max length is 1024, but you can increase to 32K. If you are using IRRPNL00 I don't think you have this limitation. (Haven't worked with this for a long time...going mostly by memory and a quick look at the TSS User Guide).
Also, wouldn't you be able to verify whether or not all the results for the resource in question ar getting returned by performing a TSS LIST(user) DATA(XAUTH,PROFILE) as well as listing the ALL record, to identify all of the target resources that are expected to be found ... and then compare that with the results that are being returned? --Joe