On Alpha and Integrity server systems, releases a user
    capability, indicating to other processes that the resource is
    now available.

    This service accepts 64-bit addresses.

    Format

      SYS$FREE_USER_CAPABILITY   cap_num [,prev_num] [,flags]

    C Prototype

      int sys$free_user_capability  (int *cap_num, struct _generic_64

                                    *prev_mask, struct _generic_64

                                    *flags);