Represents all currently active stock-sections associated with the processing of this template. That is:
stockSections[0]
The current stock-section (same as stockSection property)
stockSections[1]
The stock-section from where the current one has been started (if there was any)
stockSections[2]
The parent of the parent
...
so on
Note, this property makes sense only within some stock-section, otherwise it just returns an empty array.