Output of "fw ctl pstat" command executed in the context of a Virtual System shows "Virtual memory used" is limited - "out of 4014 MB".
[Expert@VSX:0]# vsenv 2
Context is set to Virtual Device VSX-1_VS_2 (ID 2).
[Expert@VSX:2]# fw ctl pstat
Virtual System Capacity Summary:
Physical memory used: 22% (677 MB out of 3052 MB) - below watermark
Kernel memory used: 5% (170 MB out of 2950 MB) - below watermark
Virtual memory used: 15% (605 MB out of 4014 MB) - below watermark
Used: 61 MB by FW, 544 MB by zeco
Concurrent Connections: 0% (0 out of 14900) - below watermark
Aggressive Aging is disabled
... ... ...
FWK processes are 32-bit. Therefore, they are only able to work with up to 4GB of memory.