To add on, there are certain conditions that have to be met for the start/stop system to work. Right now in the summer, if your A/C can't maintain the ambient temp you have set, the engine won't shut off. For example, if it's 95 degrees outside and you have your A/C set to 65 degrees, the truck won't shut off the engine in favor of keeping the A/C compressor running. I have ,mine set to 72 degrees usually and my engine will shut off for about a minute then start back up because the A/C needs to come back on to maintain 72 degrees.
In the winter your engine needs to warm to operating temp before the start/stop system will shut the engine off. Then if the engine gets to cold it will automatically start again.