It's not possible to share the files between the OSes. They contain information specific to the memory layout of each OS. While Windows 8 and 2012 are similar they are not the same. They have different DLLs that load into memory.
This is similar to why the hibernation file can not be moved (see How to change location of hibernation file in Windows 7?).
Raymond Chen explained the reasons why in this Windows Confidential article: The File System Paradox.
Hibernation follows a similar pattern. Hibernating the operating system means
dumping the entire contents of memory into the hibernation file; restoring
from hibernation entails sucking that file back into memory and pretending
nothing happened. Again, it's another chicken-and-egg problem: to load the
hibernation file, you need the file system driver, but the file system
driver is in the hibernation file. If you keep the hibernation file in the
root directory of the boot drive, the miniature file system driver can be used instead.