How to reserve time for unforeseen activities using JIRA portfolio?

[Rob Jansen]

Hello, 

I have multiple Scrum Teams and we plan releases of half a year. During that release I need to reserve time for bugs that pop-up during development. Every team needs this kind of buffer. How do I create a buffer for all my teams? I am not looking for e.g. shortening the release by not planning until the last sprint of that release but more for a way to have a buffer that I can adjust during the development when unforeseen work comes in.

Thanks for your suggestions.

Kind regards,

Rob