I’m not sure there is such a thing. Between my friends and my own experiences, I’ve seen too many jobs in too many markets simply evaporate to believe that there’s any kind of real security in the job market. Gone are the days when a person could work for a company for 20-30 years with a company provided retirement that could sustain.
Retirement benefits and health benefits are disappearing left and right from corporations, and even the most highly qualified people can find their jobs disappearing out from under them. They didn’t do anything to be fired, didn’t slip in performance in any way, but the job was dissolved.
I’ve seen at my school that full professors retire and new ones never take their place. Instead, adjuncts take their place, and the same holds true for other businesses.
I think the only real job security is in cultivating a variety of skills and talents for when the inevitable job shortage takes place.