If you still have the issue, try using a 64 bit Java Virtual Machine (this requires a 64 bit OS) and make sure it is being used.
To do so, edit the path to java.exe in the .bat file, so it includes the directory, e.g.
"C:\Program Files\Java\jre1.8.0_111\bin\java.exe" -Xms1024m -Xmx1024m -jar GDStash.jar