On Alpha and Integrity server systems, reserves a user
    capability, indicating to other processes that the resource is
    in use.

    This service accepts 64-bit addresses.

    Format

      SYS$GET_USER_CAPABILITY   cap_num [,select_num] [,select_mask]

                                [,prev_mask] [,flags]

    C Prototype

      int sys$get_user_capability  (*cap_num, int *select_num, struct

                                   _generic_64 *select_mask, struct

                                   _generic_64 *prev_mask, struct

                                   _generic_64 *flags);