Returns the size in bytes of the memory block needed to save the object.
HRESULT GetSizeMax(
  ULARGE_INTEGER* pcbSize  //Pointer to size of memory needed to 
                           //save object
);
 This method returns the size needed to save an object. You can call this method to determine the size and set the necessary buffers before calling the IPersistMemory::Save method.
The GetSizeMax implementation must return a conservative estimate of the necessary size because the IPersistMemory::Save method uses a fixed size memory block.
  Windows NT: Use version 4.0 or later.
  Windows: Use Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in ocidl.h.