I can't imagine what you are doing!
Best bet is to open a bug report on github, we can have detailed discussions there. Fixing it needs an example dictionary that triggers the problem.
Those sizes are .. tough. I think that it would be almost surely better to use the sqlite3 storage format for the dictionary, rather than the ascii-file. This is because the ascii file forces *all* of the dictionary to be loaded into RAM. The sqlite3 format only loads that part which is needed for the current parse (and then clears RAM after it's done) so its much much more scalable.
Thinking about it now, its clear that your graphs will never fit into RAM (or, at best, just barely fit) if you uses the plain-file format.