CICS Transaction Gateway V5 The WebSphere ... - IBM Redbooks

CICS TG thread usage
The Gateway daemon, used to receive network requests from remote Java
clients, is itself a sophisticated multi-threaded Java application. It can handle
multiple requests simultaneously and has a set of properties configured in the
CTG.INI configuration file. Two pools of threads can be configured: the
connection manager threads and the worker threads. For each connected client,
one connection manager thread is used in the Gateway daemon, and is held until
the client issues a disconnect using the JavaGateway.close() method, or is
otherwise disconnected. In order for an ECI call to be performed via an allocated
connection manager thread, a thread must be allocated from the worker thread
pool for the duration of the ECI request. This relationship is summarized in
Figure 7-6.
Java client
JavaGateway.open() Connect
JavaGateway.flow()
JavaGateway.close()
ECI
Disconnect
Figure 7-6 CICS TG threading model
Gateway daemon
Connection
Managers
Workers
Thus the connection manager threads limit the maximum number of connected
Java clients, while the worker threads limit the number of concurrent ECI calls
that can be issued by these attached clients. The initial and maximum numbers
of these connection manager and worker threads are set in the CTG.INI file using
the maxconnect and maxworker parameters. Requests from connection manager
threads for worker threads can be queued internally, but will be timed out
according to the workertimeout parameter.
Wait
ECI request
ECI reply
Chapter 7. TCP connections to the Gateway daemon on z/OS 155