Share your experience!
I have phone Xperia J model...When I first got it I could use the power saving..11.2.A.0.21 but I can not find the icon after installing power saving..WHY?? 
What power saving?A 3rd party app or built in?If you are talking about the transition from ICS to JB,first it was extended standby mode and in JB is it stamina mode.
I can not use the current power saving mode..Does a durable power in the new update mode is used??
What version of android are you on?Settings-about phone and tell here.I really do not get your problem.
ttt
You are on JB,so you have stamina mode.You can find it in settings-power management.
Can you change the language to English?I cannot understand and cannot figure out.
Yes that's the name given to Stamina mode called Extended standby Mode - Tick that box and you will then see an icon in the notification area at the top next to phone signal etc which looks like two hands holding a battery