JBE Heap Space Issues

I am having problems with heap space in the JBE when i attempt to run a build for a component where a rather large number of files need to be fetched from the repository. I see the following (abbreviated) sequence when the build begins..

2010-02-12 08:53:15 Yes: Always build a user initiated request.
2010-02-12 08:53:15 Invoking pre-build participant "com.ibm.team.build.jazzscm"
Fetching files to fetch destination " .... " ...
com.ibm.team.repository.common.TeamRepositoryException: Java heap space
at com.ibm.team.scm.client.internal.ScmServiceInterfaceProxy$2.run(ScmServiceInterfaceProxy.java:174)
at com.ibm.team.repository.client.internal.TeamRepository$3.run(TeamRepository.java:1169)
..
..
at com.ibm.team.build.internal.scm.SourceControlUtility.updateFileCopyArea(SourceControlUtility.java:365)
at com.ibm.team.build.internal.engine.JazzScmPreBuildParticipant.preBuild(JazzScmPreBuildParticipant.java:193)
at com.ibm.team.build.internal.engine.BuildLoop.invokePreBuildParticipants(BuildLoop.java:628)
at com.ibm.team.build.internal.engine.BuildLoop$2.run(BuildLoop.java:466)
at java.lang.Thread.run(Thread.java:619)

The problem occurs a few tens of seconds after the build starts, and no files seem to have been transferred to the build host.

The same JBE will quite happily run a build of a different component with a smaller number of files, so i am guessing here the problem relates to the number of files.

I could not find any obvious configuration parameter that would possibly resolve this. Any suggestions ?