Version 4.2.6 for Mainframes (Update)
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Logging Natural Sessions under CICS

This document describes how information about Natural sessions can be logged in a file which can be processed and evaluated in batch mode.

It covers the following topics:


Logging Facility

Optionally, information about Natural sessions can be logged in a file which can be processed and evaluated in batch mode.

In contrast to the online SYSTP Utility, which just gives a snap shot of the current system usage, this logging facility can be used to keep track of the Natural CICS system usage over a longer period of time.

Special Considerations

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Natural Log File Definition

The Natural log file is a sequential disk file; that is, an "extra partition destination" in terms of CICS. By default, the internal (logical) name of the log file is NLOG; this name can be changed by specifying the LOGDEST parameter in the NCMPRM macro.

The log file has to be defined in a CICS DCT as TYPE=EXTRA with associated dataset control information (TYPE=SDSCI entry in DCT). This file must also be defined in the CICS start-up JCL (DD statement in z/OS, DLBL statement in z/VSE).

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Natural Log Records

The following records are logged in the Natural log file:

Natural CICS System Restart Record

Length=96

After successful SCP system initialization, a record that holds the initialization date and time as well as other system data like the common system prefix, the number of RCBs or the number of thread groups, is written to the log file.

When this first log request fails, the Natural log file is flagged in the system directory as not available and no further logging takes place.

System restart records are written whenever the system highwater marks are reset by the corresponding system administration function of the SYSTP utility. In addition to the system start information, these records contain the terminal ID and the user ID of the SYSTP user.

Natural Session Termination Record

Length=216

On (normal or abnormal) termination of a Natural session, a session log record is written to the log file. This record is internally split into six parts:

  1. The record control part which holds the actual session statistics:

    The record control part is common to all Natural log records to distinguish the different record types. Macro NCMLOG holds the record layouts.

  2. The user session part which holds the actual session statistics:

  3. The thread group part which holds the current data of the thread group associated with the session:

  4. The thread part which holds the data of the TYPE=SHR thread used as last thread by the session (if used at all):

  5. The roll facility part which holds information about the roll facility to which the session was assigned (if it was at all):

  6. The system directory part which holds statistics about the global system usage:

By design, session termination records are stored by session date and time. This means that parts 3 to 6 of a later session record always hold more current information than those of a previous one. Parts 3 to 6 of the record are used by the log file evaluation program to refresh the corresponding information provided; that is, information on the thread group, thread, roll facility and SCB.

This technique is used to keep up-to-date information about the Natural CICS system resources in case CICS terminates in an uncontrolled manner.

The session termination log records, of course, reflect only resources which have been used by the corresponding sessions. Therefore, these records may not reflect the full SCP environment. Reports of a full SCP environment can be obtained by making a snapshot of the whole environment by either using the SYSTP System Administration Facilities or placing Natural under CICS into the CICS PLTSD (as described in the section Special Natural CICS Functionality).

System snapshot records in the Natural log file represent session termination records without session-specific information as listed under part 2.

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