Write large files

Hi to everyone.
I'm facing an OutOfMemory exception because the XML files I want to
write is too large, so I have to handle in memory too much XML objects
(generated from the XSD using XMLBeans 2.2.0). 
The use of Xms and Xmx parameters is a good workaround, but I'd like to
implement a stronger solution (in case of my file becomes larger !).
Is there a way to flush a part of XMLObjects into the XML file so that I
can free memory of marshalled objects and instanciate new ones ? Or
XMLBeans allows only "one-shot" operation ?
 
Thx a lot.
Damien.