Legal Question in Employment Law in California

Re: Is it ok for my boss to call and leave me cursing, threatening messages

Get caller ID and don't answer calls from the store on your day off. Seriously, you might have a chat with this boss when he/she is in a good mood and explain that, on your days off, you'd appreciate not being bothered, except for an emergency. Of course, also explain that your family hears the messages and it disturbs your children (assuming you have some), or your spouse. If you feel really bold, you could suggest the boss go to an anger management class. Good luck.