URL-escape a var with JSTL

Hello,

I need to URL-escape a variable in JSTL, and am not having much luck finding the way to do it.

For example, I currently do:
<c:set var="foo" param="${param.foo}"/>

Since "foo" param may include some funky characters, I need to URL-escape that.  So I'm looking for something similar to:

<c:set var="foo" param="${param.foo}" escapeXml="true"/>

What's the right way to URL-encode a variable with JSTL, without resorting to scriptlets?
Or is the only option to use escapeXml="true" when doing c:out?

Thanks,
Otis