Arguments

 

key

   Address of a variable that receives the key value. This value
   is used in calls to tis_getspecific() and tis_setspecific()  to
   obtain and set the value associated with this key.
 

destructor

   Address of a routine that is called to destroy the context value
   when a thread terminates with a non-NULL value for the key. Note
   that this argument is used only when threads are present.