[hunchentoot-devel] printing to *standard-output* in a multithreaded environment

I wonder is it save to have a macro like this: (defmacro with-html (&body body) `(with-html-output-to-string (*standard-output* nil :prologue t) ,@body)) with SBCL which is multithreaded. What happens when multiple users connect to the server and the requests are served using the macro above. I mean how do multiple threads share the *standard-output* in this case? Or should I create a new stream per request? Thank you, Andrew