MYSQL Thread_Cache_Size=0

The site doesn't seem to be affected in any major way but am concerned that it should be corrected.
MySQL:

• key_buffer_size  = 1073741824  - OK 
• max_heap_table_size  = 16777216  - OK 
• tmp_table_size  = 16777216  - OK 
• thread_cache_size   = 0  - FAIL (must be > 0)