Accessing stacks without opening

[Marty Knapp]

So it appears that you can set custom properties of a stack and "put" 
information into fields of stacks that are not open, from a stack that 
is open. I just did it by accident! That being the case, is there 
anything that I should be aware of when doing this? Is the referenced 
stack loaded into memory? Is this considered bad form?

Thanks,
Marty Knapp