I have been lucky enough to stay at my jobs for a few years....then make a change to a new job before even getting close to being laid off. This came out of the blue to everyone of us (except management of course).
They called it a "restructure" of the company.....but who knows the real reasons.
Let's just say even those that didn't get laid off are worried and most likely will be looking soon....they just get a bit longer to work and still get a paycheck.