>The OP claims that no files larger than 2.1G were produced when using
libsndfile.

Are you trolling? OP did not claim that libsndfile was to blame.
No one has. Don't try to twist what people write so that it
sounds like something else.

> However, it doesn't matter what you wanted to point out, important only
> is that, if neither libsndfile, nor wav does cause the issue the OP
> experienced, then something else most cause the trouble. Right?

I don't know why it stopped at 2GB. Maybe it's something in the jackrec 
program, but that's unrelated since we were talking about jack_capture,
not jackrec. And in jack_capture, the limit is 4GB (jack_capture also uses
libsndfile). I know this quite well since I'm the author of jack_capture, and I've
tested the 4GB barrier many times to ensure jack_capture handles it correctly.