A life sentence merely means that whenever you are released (whatever the term) you are basically on probation till you die, if you fail to live a crimefree life you can be returned to continue a sentence.
you can actually be recalled even without comitting further crime although I'm not sure if this has ever happened
True, it's the threat that is the "life" part though, which is what i was trying to explain.
This is the general misconception mostly down to the wording or reporting.