Unfortunately the information is scattered. There is some in the IS Administrator’s Guide, the EDI user’s guide, the Trading Networks Administrator’s Guide and Concepts Guide, and the Built-in Services Reference (in service descriptions and usage notes).
There is a GEAR 6 (not 6.5) implementation guide that has some information about large document handling as well. There is a large doc handling sample available on Advantage. It’s in the WmSamples I believe.
Basically, you’ll want to ensure that the XML content handler streams the XML doc to disk and that your service uses a node iterator to process the stream in chunks.
I know this isn’t much info but I hope it is enough to get you started on the right path.
#webMethods#Integration-Server-and-ESB#Flow-and-Java-services