How to read big Ontology file into the OntModel ?

[月之子]

As we know ,if we want to parse a OWL file ,we always read in it and then 
create a OntModel with the ModelFactory. But this will encounter a problem when 
reading a large file,for example the file size is larger than 50MB.Java will 
throw an exception for : JAVA heap space,because of the limitation of memeory. 
So is that mean I can't parse large OWL file with JENA and get the OntModel? If 
it can , how could I achieve it ? Thanks