How many is the maximum available memory for building light with the Unreal Engine?

How many is the maximum available memory for building light with the Unreal Engine?
And where can I setting that option?

windows7 / 2x xeon E5 / geforce GTX 1080 Ti 12BG / memory 128GB

you need to change first of all windows 7 to:

  • Windows 7 Professional 64-Bit 192GB
  • Windows 7 Ultimate 64-Bit 192GB
  • or
  • Windows 7 Enterprise 64-Bit 192GB

since the OS is limiting the max amount of memory