spectre 4g memory

I using Cadence Spectre PSS & PNOISE simulation tools.
When PSS, there is always a error "Insufficient memory available."
and simulation halt.

My work setting is Xeon workserver + Linux + Cadence, and Memory is 4G.

Can you tell me why?

Thanks very much!

I found why
When PSS simulation, if the fundamental frequency is low (100KHz), PSS need huge memory.
Can someone give me a resolvent under not adding memory?