Out of Memory Error is a Java Runtime error. We're working on reducing Xalan's memory footprint... but realistically, some tasks will always take a lot of storage, and Java's default settings may not be enough. Tell your Java environment that it is allowed to use more heap space. Depending on which Java you're using, this can be be done with the -mx or -Xmx command line switches. (If in doubt, specify both and Java will probably ignore the one it doesn't know how to use.)
I generally run with -mx64M -Xmx64M. That's probably overkill.
