clearing the cache in zms 2.11

Hello,

I want to clear the whole site cache in an zms 2.11 instance from an  
request parameter, but with no effect.

<dtml-if "REQUEST.has_key('clear')">
   <dtml-call "clearCache()">
  </dtml-if>
"clearCache()" will throw an error.


Has the API changed? Can't find any caching related entries in the ZMS  
API Documention in the ZMI anymore...

Thank you!
Frank

ps. is it possible to clear the cache periodically every day from  
within the ZMI. I remember, a former Version of ZMS had this feature.