No Insufficient Memory Promble in PSS/Pnoise simulation

Hi,

I have some promblems on VCO Post-simulation of PSS and Pnoise. The Frequency of the VCO is 20GHz. When I simulate the schematic, everything is good. But when I comes to Post-simulation, there will always be the error "no insufficient memory".

At first, I can't finish the pss and one of my classmates told me to set a swapfile. It's very useful and I can finished pss in about an hour. But now, I can finish the pnoise. 

My parasitic resistor number is about 70,000. I try to run PEX with the output "C+CC", and the two simulation can finish quickly. So, is the parasitic resistor number is too much? Or there is something wrong in my setup.

My setup is followed:

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pss

engine shooting

Beatfrequency 18.46GHz(I have simulate transient to be sure of the oscillating frequency.)

Number of harmonics 11

Accuracy Defaults conservative

tstab 40n(it is stable nearly 20ns.)

Oscillator ON and OP

Options

swapfile set already

method gear2only

tstabmethod gear2only

Pnoise

sweeptype default relative harmonic 1

frequency sweep range 10k 100M

  Points per Decade 10

Maxmum sideband 11

voltage ON OP

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And I also select "Run with 64 bit binary" in the Environment setup

This problem has confused me for a long time, and I have googled it, but didn't find something helpful.

 I would appreciate it very much if anyone would help me with it.

As I'm in UTC+8, so maybe I can't reply immediately.