MPE/iX 5.5 Operating System Limits

Telnet/iX Limits
Within each functional area, one or more limits are stated along with the system table or
resource which imposes the limit. Using the number that corresponds to the particular
limit you are interested in, you may refer to a written description of that resource which is
also included within the section. If you see a '~' in front of a stated limit, this implies that
the limit is variable or approximate. Generally, limits tagged with a '~' character are
derived based on a (sometimes) formula. For most of these formulas there are several
variables which can on be estimated, modeled or assumed. The actual limit on your
system could be quite different. In these cases, you should definitely refer to written
descriptions.
NS transport & netipc/BSD sockets - limits
This section describes the system limits by the Sockets layer of the Operating system.
This Layer is interface between user applications and the network protocols. The
applications can use either NetIPC intrinsics or the BSD sockets intrinsics to acess the
services of the underlying network protocols,like TCP,UDP etc.,
The maximum number of sockets ,that can be created on MPE 6.0 is 8192. When a
process forks, the child inherites the parents open file descriptors,including the sockets.
These sockets are shared by the parent and the child process. Each such socket is
associated with an alias socket record.
The max number of such alias sockets is set to the MAX_PIN value of the system. The
value of MAX_PIN for MPE 6.0 is 8192.
# MAX_NUM_WAITQ_ENTRIES := max_pin (8192)
The maximum data that can be sent or received through the SEND/RECV system calls is
30000 bytes.
SK_MAX_DATA_LEN = 30000; { max # of bytes in send/recv }
Nwtm (network type manager)
This is type manager layer which interfaces the socket layer with the underlying protocol
layer. On MPE, each file type has unique type manager, which handles the operations on
that file. NWTM is the sockets file type manager. The file system is aware of the
presence of NWTM and when user applications issues a read/write against a socket, the