Investigate larger GC heap sizes and support environment parsing

[ekrich]

Investigate the possibility of expanding this to more memory: Terabyte, Exabyte, Petabyte.

I can remember the time when a gigabyte of memory was an infinite amount, times change.

As discussed here: #4338
The line "system memory maximum" covers the whine "I specified 1PB
and all I got was 512MB".