A Win32 process running under Win64 can use up to 4 GB if IMAGE_FILE_LARGE_ADDRESS_AWARE is set, make sure Visual Studio Project Properties have this enabled:

Configuration Properties->Linker->System:

“Enable Large Addresses”

set to:

Support Addresses Larger Than 2 Gigabytes (/LARGEADDRESSAWARE)

Reference

https://social.msdn.microsoft.com/Forums/en-US/bd656b83-b715-4e08-af4d-c6372979fa9a/increase-memory-for-visual-studio-2010-c?forum=Vsexpressvc