Multi-stack (CINET)

z/OS® Communication Server allows you to have multiple TCP/IP stacks concurrently active on a single system. This is referred to as a CINET setup.

When multiple TCP/IP stacks are active on a host system, it is important that Debug Manager and Debug Probe are using the same TCP/IP stack in order for them to communicate. Debug Engine (on the client) must also be able to communicate with Debug Manager. By default, Debug Manager binds to every stack available on the host to simplify matching Debug Probe and Debug Client setup.

If this is not desired, then stack affinity can be used to instruct Debug Manager to bind to a single specified TCP/IP stack. Stack affinity is set with the _BPXK_SETIBMOPT_TRANSPORT environment variable, which must be passed on to Language Environment®. You can set stack affinity by adjusting the startup command in the started task JCL:
//DBGMGR   PROC PRM=,
//*           LEPRM='RPTOPTS(ON)',
//            LEPRM='RPTOPTS(ON) ENVAR("_BPXK_SETIBMOPT_TRANSPORT=TCPIP")',
//            TZ='EST5EDT',
//            CLIENT=5335,
//            HOST=5336,
//            HLQ=EQAW
Notes:
  • BPXK_SETIBMOPT_TRANSPORT specifies the name of the TCP/IP stack to be used, as defined in the TCPIPJOBNAME statement in the related TCPIP.DATA.
  • Coding a SYSTCPD DD statement does not set the requested stack affinity.