What is a size of mac_length and mac_key_length for TLS cipher suites HMAC using SHA384 and SHA512? i failed to find explicit definition of hash output size and mac_key_size for hmac based on SHA384 and SHA512.
RFC5246 specifies:



but defines only
Given that MD5 has a size of 128 bit (16 bytes), SHA-1 of 160 bits (20 bytes) and SHA256 of 256 bits (32 bytes) and that these numbers are exactly reflected in the mac_length and mac_key_size I would assume that these sizes reflect the output size of the hash used. This also matches the definition of the HMAC used in TLS where the last step is to apply the hash and use its full output as result. Similar the HMAC definition recommends the output length of the hash as the minimal (and also probably most suitable) key length.

With this in mind the size for SHA-384 will be 384 bits (48 bytes) and for SHA-512 512 bits (64 bytes).