How to check if a TCP port is already in use or reserved to a different job/STC
Article ID: 130242
CA Dynamic Capacity Intelligence
When customizing a CA Dynamic Capacity Intelligence (DCI) control region JCL, a TCP port number must be provided. There are some TCP commands that can help determine if a port is already in use.
IP ports cannot be shared between different regions. Moreover, a port can be reserved to a specific region.
DCI 1.5 and above on z/OS
NETSTAT CONN (PORT nnnn command shows if the port is already in use; for example: NETSTAT CONN (PORT 21 MVS TCP/IP NETSTAT CS V2R3 TCPIP Name: TCPIP User Id Conn State ------- ---- ----- FTP 00244E1D Establsh Local Socket: ::ffff:nn.nnn.nn.nn..21 Foreign Socket: ::ffff:mm.mmm.mm.mm..pppp
NETSTAT PORTL (PORT nnnn command shows if the port is reserved to a specific jobname, for example: NETSTAT PORTL (PORT 21 MVS TCP/IP NETSTAT CS V2R3 TCPIP Name: TCPIP Port# Prot User Flags Range SAF Name ----- ---- ---- ----- ----- -------- 21 TCP FTP DA
The above commands can be run in batch: //NETSTAT EXEC PGM=IKJEFT01 //SYSPRINT DD SYSOUT=* //SYSTSPRT DD SYSOUT=* //SYSTERM DD DUMMY //SYSTSIN DD * NETSTAT CONN (PORT 21 NETSTAT PORTL (PORT 21 /*
If the DCI Control region is started with a TCP port that is "reserved" to a different region, then the following message is returned: DCI0999E: ERROR BIND : (0000000D/FFFFFFFF)