With this Hibernate commit to SimpleValue.java, the configuration property Environment.PREFER_POOLED_VALUES_LO is passed on to the id generator's parameters and thus available to the id generator's own Configure() method: https://github.com/hibernate/hibernate-core/commit/b0708314a91a200041f4362943d8de1bd47a443d#diff-4
NHibernate doesn't seem to have something corresponding to this "mappings" instance available in the SimpleValue class. For Hibernate, it was added during a large refactoring in May 2010 (heavy page): https://github.com/hibernate/hibernate-core/commit/421789ddcd906e806bf901fea9d9e713daebd51a Is this a reasonable way to proceed in NHibernate, given that the "mapping" object is not available in SimpleValue: https://github.com/obbe80/nhibernate-core/commit/f704bfc8a4b4dbf6ade12078ed6138dad4e7c35e /Oskar
