Gatttool automatically stop listening to notifications

Hello,

I'm trying to register to notifications from a peripheral with "gatttool" command, for an undefined time.
I correctly receive the notifications when listening, but the problem is that gatttool stop listening after 25s and automatically unsubscribe from the peripheral's characteristic.

I register like this :
gatttool -b 4F:2B:CF:4F:EB:7C --char-write-req --handle=0x0038 --value=0100 --listen

Is there some GATT configuration that define a timeout for notification listening ?
How can I do to be able to stay registered and listening until I manually unsubscribe ?

Thanks,

Jérémie