There is a thread
here (posted at the end of December), PHP7 just came out at the beginning of December; if you take in to account the
PHP7 Changelog I wouldn't even really consider running this on a production server until a lot of testing has been done against it; a lot of hosts are just now rolling out PHP 5.6.
PHP7.0 - Released 03 Dec 2015
PHP7.0.1 - Released 17 Dec 2015
PHP 7.0.2 - Released 07 Jan 2016
As UBB.threads 7.6.0 is just waiting on several updates, and PHP7 came out at the beginning of December, no testing has been done (at all) to test compatability; one should assume it won't work however until users have had the time to test on a PHP7 system.
At this point, we're developing on PHP 5.6.17 (my VPS), 5.4.45 (UBBDev), and I believe Isaac's server is 5.6 with the option of 7.0 through his provider. The minimum PHP requirement for 7.6.0 is PHP 5.3