NoMachine provides convenient access to interactive sessions via the drop-down menus. Choosing one item runs a 'wrapper' script with default parameters to start your sessions (for that reason, we call them default submission scripts). But if you need a larger RAM footprint than provided, you must write a custom submission script (see this document), which provides at least the queue name, the program to run, and your requested RAM amount. For example, to run a 30 GB RStudio session, one would use the following command:
bsub -q interactive -Ip -W 6:00 -R "rusage[mem=30000]" /usr/local/apps/R/rstudio/v0.98.493/bin/rstudio
(Note: ignore the word wrap ... the above command should all be on one line)
Please see our Starting Interactive Jobs page for more information.