What is the setting that forces ConTeXt to keep footnotes on the page where
they are called?

In the following example,

\setupinteraction[state=start]
\setupnotation[footnote][interaction=yes,way=bytext]

\setupnotation[footnote][split=verystrict]

\starttext
\dorecurse{50}{some text\footnote{a footnote} }
\stoptext

the call for note 42 and the note itself are on different pages. I realize
that this may be an extreme case, but, regrettably, that is what I have in
a review that I am typesetting.

Alan