NX Nastran memory allocation via NX is done on the Solver Parameters dialog. On the Simulation Navigator, RMB on the Solution and select "Edit Solver Parameters...". In the nastran Command Keywords group, there is a string input for memory. If you enter a real number, it will be interpreted as the number of Nastran Blocks. To enter a more user friendly value, you can add a unit after the number - typically MB for megabytes or GB for gigabytes. The following image shows the dialog with the NX default 400 megabyte request. You would want to increase this value (i.e. change 400MB to 4GB to request 4 gigabytes of memory).