`the stacksInUse`

The<code> stacksInUse </code>property returns a return-separated list of stacks that have been inserted into the message-passing path via the<code> start using </code>command.  Each stack appears in the order it will receive messages. The<code> stacksInUse </code>contains the full path names of the stacks being used.

HyperCard can use up to 16 stacks.

Note: You can’t compact a stack that’s being used.