Managing the number of sockets

IMS Connect supports from 50 to 65,535 sockets at one time. Within that range, you can define both a maximum number of allowable sockets and the point at which IMS Connect issues warnings when the number of sockets approaches the maximum.

The total number of sockets that IMS Connect supports across all TCP/IP ports at the same time is set by the MAXSOC parameter in the TCPIP configuration statement of the IMS Connect configuration member. If the number of sockets reaches the maximum, IMS Connect refuses any new connections and issues message HWSS0771W. After the number of connections falls below the MAXSOC value, IMS Connect resumes accepting connections.

Because IMS Connect uses one socket on each TCP/IP port for listening, the maximum number of physical connections that IMS Connect supports is the MAXSOC value less the number of TCP/IP ports. For example, if you specify MAXSOC=80 and have five TCP/IP ports, 75 physical connections can be made.

By default, the MAXSOC parameter sets the maximum number of sockets at 50.

As the number of sockets approaches the maximum allowable number, IMS Connect issues warnings at a warning threshold set by the WARNSOC parameter and, if the number of sockets continues to rise, at increments set by the WARNINC parameter thereafter. Both the WARNSOC parameter and the WARNINC parameter are specified on the TCPIP configuration statement in the IMS Connect HWSCFGxx PROCLIB member.

You can display the current values of the warning threshold and the warning increment, as well as the current number of open sockets for an instance of IMS Connect, by issuing any of the following commands:
  • IMS Connect WTOR command VIEWHWS
  • IMS Connect z/OS® command QUERY MEMBER
  • IMS Connect type-2 command QUERY IMSCON TYPE(CONFIG)
You can also display the current number of sockets on a given port by issuing any of the following commands:
  • IMS Connect WTOR command VIEWPORT
  • IMS Connect z/OS command QUERY PORT
  • IMS Connect type-2 command QUERY IMSCON TYPE(PORT)

Even when there are no active client connections on a port, when displaying the current number of sockets, IMS Connect ports always show one open socket: the port listen socket.

The IMS Connect SSL port shows at least two sockets: the port listen socket and a socket that represents the SSL-related file descriptor. When the IMS Connect SSL socket receives its first connection, an additional SSL-related file descriptor is created, so that the IMS Connect SSL socket shows four sockets for the first client connection: the port listen socket, two file descriptors, and the client connection socket.