This linker flag gives a 32 bit application the full 4GB address space, effectively doubling the randomization provided by ASLR and making heap spraying slightly more difficult. See also: - https://msdn.microsoft.com/en-us/library/wz223b1z.aspx - https://sourceforge.net/p/mingw-w64/mailman/mingw-w64-public/thread/51DF8445.9050105@gmail.com/