According to the documented configuration options (http://xmlgraphics.apache.org/fop/0.95/configuration.html) there should be one called "cache-file". But it is not evaluated in the responsible class FopFactoryConfigurator / FontManagerConfigurator. In some environments it is a useful option because there may be no user directory which is used by default.
the same problem occurs on linux environment
resetting P2 open bugs to P3 pending further review