Samba 2.2.0 for Digital Unix 4.0b

[system PRIVILEGED account]

Dear Colleagues,
I have some servers here, and one of them has Digital Unix 4.0b. The
problem is that I cant install Samba 2.2.0 correctly. When I try to run
the make command, I receive the following message:
###
Compiling smbd/server.c
In file included from include/includes.h:310,
                 from smbd/server.c:22:
/usr/include/prot.h:71: acl.h: No such file or directory
*** Exit 1
Stop.
###
I know that the process is looking for /usr/include/prot.h file, however
I dont know what to do. What package do I need to install to solve this
problem??
Thanks and regards,
Luis Marcelo Achite