This object contains an appropriate value to be used
for hpnicfmplsLabelStackIndex when creating entries in the
hpnicfmplsLabelStackTable. The value 0 indicates that no
unassigned entries are available. To obtain an
hpnicfmplsLabelStackIndex value for a new entry, the
manager issues a management protocol retrieval
operation to obtain the current value of this
object. After each retrieval operation, the agent
should modify the value to reflect the next
unassigned index. After a manager retrieves a value
the agent will determine through its local policy
when this index value will be made available for
reuse.