Share your experience!
This might interest you
http://talk.sonymobile.com/t5/Software-Updates/Lollipop-New-Features/td-p/955490
dont know, but i use it often on kitkat (press multitasking button(at right bottom, it showed all open apps in multitasking and on the bottom of screen there was button to clear all)). now when there´s a lot of opened cards in multitasking i have to close them one by one. with clear all it took just one click
I remember the option but only for Z3 and Z2(?).