Last time my job was threatened, I spent a few weeks brushing up on my algorithms, going through coding challenges, reimplementing the basics (in my case, a concurrent consumer-producer queue, an IPC mechanism, etc.)

I'm an experienced systems developer with a pretty good resume, I didn't want to look stoopid if I was asked any such question in an interview.

Worked pretty well. I wasn't laid off but I ended up changing job for something more fun than my then position.