(* LKSIZE should match sizeof(semax_conc.tlock).  *)
Definition LKSIZE:= (2 * size_chunk Mptr)%Z.
Definition LKSIZE_nat:= Z.to_nat LKSIZE.

Lemma LKSIZE_int : (size_chunk Mint32 < LKSIZE)%Z.
Ltac lkomega := pose proof LKSIZE_pos; pose proof LKSIZE_int; simpl in *; try omega.