Controlling z/OS UNIX System Services (USS/OpenEdition) Support

z/OS has introduced major changes and enhancements to the UNIX for z/OS (OpenEdition) environment to make it part of the MVS core. Consequently, certain applications, such as IBM FTP, were converted to use the USS (Unix Services for z/OS). As a result, IBM FTP stopped issuing allocation and deallocation messages to the JESYSMSG spool dataset.

Control-O provides a special interface to support dataset-triggering events originating from UNIX.

The Unix for z/OS interface is shared by all Control-O installations in the LPAR and is version-independent. The first Control-O subsystem to initialize loads the Unix for z/OS interface module to common storage. This interface is later used by all other Control-O subsystems. Upon startup, every Control-O subsystem registers itself with the Unix for z/OS interface. This registration mechanism enables the Unix for z/OS interface to recognize all the available Control-O subsystems and to call them when a new process is created by a fork/spawn request and associated with a BPXAS initiator (for example, when a new ftp session has started). The Control-O monitors are called one by one in the order that they registered with the interface. The first Control-O subsystem to have a matching rule for this address space will monitor it for z/OS dataset-triggering events.

When a Control‑O subsystem shuts down, it removes itself from the Unix for z/OS interface. The last Control‑O subsystem to shut down removes the Unix for z/OS interface from common storage.

The following sequences of messages indicate that the Unix for z/OS interface was successfully installed:

• for the first Control‑O subsystem to initialize

  CTO820I INITIALIZATION OF OPENEDITION SUPPORT STARTED

  CTO821I OPENEDITION INTERFACE MODULE SUCCESSFULLY LOADED

  CTO822I SUBSYSTEM REGISTERED WITH OPENEDITION INTERFACE

  CTO823I INITIALIZATION OF OPENEDITION SUPPORT ENDED SUCCESSFULLY

• for any subsequent Control‑O subsystem

  CTO820I INITIALIZATION OF OPENEDITION SUPPORT STARTED

  CTO822I SUBSYSTEM REGISTERED WITH OPENEDITION INTERFACE

  CTO823I INITIALIZATION OF OPENEDITION SUPPORT ENDED SUCCESSFULLY

The following sequences of messages indicate that the Unix for z/OS interface was successfully deactivated:

• for any Control‑O subsystem except from the last subsystem to shut down

  CTO830I DEACTIVATION OF OPENEDITION SUPPORT STARTED

  CTO831I SUBSYSTEM REMOVED FROM OPENEDITION INTERFACE

  CTO833I DEACTIVATION OF OPENEDITION SUPPORT ENDED SUCCESSFULLY

• for the last Control‑O subsystem to shut down

  CTO830I DEACTIVATION OF OPENEDITION SUPPORT STARTED

  CTO831I SUBSYSTEM REMOVED FROM OPENEDITION INTERFACE

  CTO832I OPENEDITION INTERFACE MODULE REMOVED

  CTO833I DEACTIVATION OF OPENEDITION SUPPORT ENDED SUCCESSFULLY

Control‑O enables the operator to start and stop the Unix for z/OS interface using the Modify operator command. Usually, there is no need to intervene with the default processing performed by Control‑O. The following operator commands are available:

The STARTOE command instructs a Control‑O subsystem to restart the Unix for z/OS interface. This includes initializing the interface (if no other subsystem has initialized it) and/or registering the current subsystem with the Unix for z/OS interface. If the STARTOE command is issued for a subsystem that is already registered with the Unix for z/OS interface, the following message is generated:

The STOPOE command instructs a Control‑O subsystem to deactivate the Unix for z/OS interface. This includes removing the current subsystem from the Unix for z/OS interface and removing the Unix for z/OS interface from common storage if no other subsystem is using it. If the STOPOE command is issued for a subsystem that is not registered with the Unix for z/OS interface, the following message is generated:

If the STOPOE command is issued when the Unix for z/OS interface is not installed, the following message is generated:

The STOPOE,FORCE command instructs Control‑O to remove the Unix for z/OS interface from common storage even if one or more Control‑O subsystems are still registered with it.

Control‑O also provides Started Procedure CTOOEDSC. This procedure can be started from the console using the START command. Procedure CTOOEDSC acts like a STOPOE,FORCE command and removes the Unix for z/OS interface regardless of any registered subsystems. The STOPOE,FORCE command and procedure CTOOEDSC must be used only in case of emergency.