IPersistStream::GetSizeMax method (objidl.h)

Retrieves the size of the stream needed to save the object.

HRESULT GetSizeMax(
  [out] ULARGE_INTEGER *pcbSize
);

[out] pcbSize

The size in bytes of the stream needed to save this object, in bytes.

This method returns S_OK to indicate that the size was retrieved successfully.

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 IPersistStream::Save method.

The GetSizeMax implementation should return a conservative estimate of the necessary size because the caller might call the IPersistStream::Save method with a non-growable stream. This method retrieves the maximum number of bytes in the stream that will be required by a subsequent call to IPersistStream::Save. This value is sizeof(ULONG)==4 plus sizeof(WCHAR)*n where n is the length of the full or partial URL string, including the NULL terminator.

IPersistStream