The max pool size

HI

Since we changed a tomcat application with a Oracle DB version 12.1 (before was an 11.2 instance) both run on Linux X86_64  RH 6.4,  we get an error (below ) into the tomcat log . (max pool size is currently 20)

How could we check this value ? is there a way to verify if some Initialisation Parameters value have to be increased  ?

thanks regards

Giorgio

2016-05-12 16:09:47,354  INFO jruby.rack http-127.0.0.1-8045-9
ActiveRecord::ConnectionTimeoutError (could not obtain a database connection within 5 seconds (waited 5.001 seconds). The max pool size is currently 20; consider increasing it.):
  gems/gems/activerecord-3.2.14/lib/active_record/connection_adapters/abstract/connection_pool.rb:258:in `checkout'