I don't think pega has published any tuning document specific to a specific OS platform. What application server are you using? If it is Redhat JBoss, Redhat may have some documents (independent of pega). I do know there are a lot of customers running on Redhat 6/7 smoothly, even in production environments. Any known issues should have been captured in the platform guide. The application performance tuning is a significant undertaking, there is no "one size fit all" magic parameters.