I have full time job and I am thinking about getting a patent on my own and licensing it. It has no connection to my full time job. Do I need to tell my employer that I am licensing a patent. Does patent license count as secondary employment.
This may deal with your employment contract. For most jobs I'm familiar with what you do on you own time is your own business. This assumes it is unrelated to your company's business and you aren't using any proprietary information or tools (like your work PC). That said, I've heard of examples where a company tries to claim ownership of an employee's intellectual property.
This also may depend on where you live. I hope you are working with a patent attorney in the prosecution of your patent application. That attorney may be able to guide you with respect to your current employer. If not, you may want to talk to an attorney. Otherwise, employment law and contracts are off topic on this site. You might get some useful feedback from the Law SE site. I am not an attorney and this is not legal advice.
This probably heavily depends on the country you are in. In Germany you have to tell your employer that you are patenting something and you have to give your employer the chance to license that patent. Only after your employer refuses to license your invention you can do whatever you want with it. Whenever the invention is based on proprietary information that you got hold of because you work for that employer the situation may be different.