Charles Mills (and others) wrote about using FREEPOOL and/or RMODE31=BUFF. I will dig into those.
To Mike Hochee: I can't leave the file open. The calls to the API are atomic and have no persistence, so I don't know if this is one invocation of many, or the one and only. The good news is that this isn't actually much of a problem, because in normal usage with this API, you'd either terminate once you start getting errors, or you'd be passing a message buffer so you can return those errors to a client. It doesn't make a lot of sense to keep calling it with errors and ignoring them (that is, letting them fall into SYSPRINT). But of course I still want to fix it. Thanks to all for the suggestions. I would not have tripped over either of those any time soon! .phsiii