Accounting Circuit Breaker

I would like to understand the behaviour of the "Accounting Circuit Breaker" more.
Unfortunately I could not find any good information on it so far.

The documentation
https://www.elastic.co/guide/en/elasticsearch/reference/6.8/circuit-breaker.html
does not explain what happens when the limit is reached.

From what I've understood, this Circuit Breaker is directly linked to the (lucene) segment size.

So, when we hit the Circuit Breaker threshold, does this just cause a cache eviction or does ES require the lucense segments to be in memory and we are like to encounter a failure of the entire node?

ElasticSearch Version: ES 6.6.1