Non-Shared Memory Settings in the IDE

Limit memory use
Specify whether you want the run-time system to restrict the amount of memory available to the application
Memory limit
Specify the amount of memory to allocate to dormant programs in the run-time system. A dormant program is one which has been logically cancelled by the run unit, but has not been physically unloaded from memory. A dormant program can be executed considerably faster than one which has to be loaded from disk, so this memory allocation is effectively a cache of programs that have been cancelled but might be needed again.

When the size you specify is reached, all cancelled programs are unloaded, thereby releasing all of the dynamically allocated memory. If you specify a size of 0, all cancels will physically unload the program from memory.