If you are deploying in the Mendix Cloud, the instructions can be found here.
If you are running your app in a Docker, you can pass that as an environment variable as described here.
Although I have no experience with on premises Unix deployments, it seems the documentation can be found here. Furthermore, in this example m2ee yaml, you can search for connection pooling and see how you should configure it.
try increasing the pool size as it is 50 for you now
check out this document you may find what you need