A running z/Server consists of at least two started tasks:
The holder address space TAURHLD provides the necessary infrastructure and user administration control structures using a common access data space. It is non-swappable. It is also used to start and stop the scheduler and the user server address spaces.
The scheduler address space provides the requested client services or starts other z/Server user server address spaces to run a user specific ISPF application. There can be more than one scheduler running under the umbrella of the same holder address space.
A user server address space is started first to download the master configuration file to the Eclipse client and whenever the Eclipse client requests a specific REXX exec to be run. Each client can have more than one user server running for that TSO user ID.
A z/Server scheduler address space for CEA-launched TSO user address spaces (CEA scheduler in short) provides the services to start a TSO user address space. It is started when the Eclipse client calls the action “Launch ISPF” from zExplorer’s context menu in Remote Systems View, provided the port specified in the MVS Explorer settings under “ISPF launcher port” maps the parameter PORT specified in the CEA scheduler (CEASCHED) configuration.
The CEA-launched TSO user address space runs like any TSO address space under the user id of the connected user. The client communicates with this address space using the CEA scheduler and a z/OS USS message queue.