[Zope] store data as long as the user is logged on

hi, i need to store some data as long as the user is logged on to zope. how can i achieve this? using the session is not a good idea, because some parts of the code simply call session.clear() (i did not write that part). if everything fails, i can use a singleton where i put a dictionary based on some-kind-of user-id... but i'd like to avoid that if possible (don't want to think about the multi-user-asking-at-the-same-time problems).. is there any place where i could attach my data structure? thanks, gabor