Recommend way to start a php session in an EE module?

What is the recommended way to start a php session in an EE module.

I am using EE 2.9.4 and have a custom module. In the constructor I call session_start(). When I look at the cookie that gets created the cookie path is wrong. It is set to the path of the page instead of “/”.

When I call session_start in a plain php app the default behavior of session_start is to set the cookie path at root “/”.