CPU CORE Thread will help RMAN backup when using the Channel.

You have 4 CPU sockets, each CPU can have, up to, 12 cores and each core can have two threads.

Your max thread count is, 4 CPU x 12 cores x 2 threads per core, so 12 x 4 x 2 is 96. Therefore the max thread count is 96 and max core count is 48.

How to find out the cpu

$lscpu