is libressl/libtls full duplex or half duplex from the application writing perspective?

[cartazio]

Hello! In the context of a high concurrency application i'm at the beginning of writing, i'm of course using libtls and friends. I've been trying to understand if

1. TLS can be treated as providing full duplex sockets to the application
2. if TLS the protocol can be full duplex during the bulk of a session, do libressl/libtls provide a full duplex capability to the application (a cursory hunt for locks and mutexes in the code base doesn't give me much clarity here)

many thanks!
(also if this is documented somewhere already please let me know!)
-Carter