On 01/10/18, Benny Pedersen said the following...   
       
    BP> so nearly all is now considered unstable, 4.9.72 maked a stable kernel   
    BP> for me, 4.12.12 was masked stable but was not stable   
      
   Gentoo stable masking is pretty inconsistent. Sometimes they sit on packages   
   for years and other times they unmask with a minimum of testing and break   
   large swaths of the userbase.   
      
   4.9 is a long term release series receiving backported updates like meltdown/   
   spectre mitigation. You should be fine on that unless you specifically need   
   features implemented in later kernels.   
      
   Debian stable is also on 4.9 but does have access to 4.14 backported from   
   buster.   
      
   --- Mystic BBS v1.12 A38 2018/01/01 (Linux/64)   
    * Origin: Subcarrier BBS (1:249/400)