You will find here the environment variables that change the default behavior of the NATS C Client library.

Name	Effect
`NATS_DEFAULT_TO_LIB_MSG_DELIVERY`	On nats_Open, the library looks for this environment variable. If set (to any value), the library will default to using a global thread pool to perform message delivery. See natsOptions_UseGlobalMessageDelivery and nats_SetMessageDeliveryPoolSize.