Zero is currently defaulting to `MaxRAM=1G` on all machines. It is set in `compiler_globals.pd` under `#if !defined(COMPILER1) && !defined(COMPILER2) && !INCLUDE_JVMCI`.

Zero supports lots of GCs, and there is little sense to penalize it unnecessarily with too small heaps. After JDK-8292847, this would allow G1 with reasonable heap size on most machines.