QHST History Log

The history (QHST) log consists of a message queue and a physical file known as a log-version. Messages sent to the log message queue are written by the system to the current log-version physical file.

The history log (QHST) contains a high-level trace of system activities such as system, subsystem, job information, device status, and system operator messages. Its message queue is QHST.

Log-Version

Each log-version is a physical file that is named in the following way:

Qxxxyydddn

Where:

xxx is a 3 character description of the log type (HST)

yyddd is the Julian date on which the log-version was created

n is a sequence number within the Julian date (0 through 9 or A through Z)

When a log-version is full, a new version of the log is automatically created.

Note: The number of records in the log-version of the history log is specified in the Maximum records in history log (QHSTLOGSIZ) system value. This system value also supports a *DAILY option which creates a new version each day.

Format of the History Log
A database file is used to store the message sent to a system log. Because all records in a physical file have the same length and messages sent to a log have different lengths, the messages can span more than one record. Each record for a message has three fields:
Performance information and QHST
Performance information is not displayed as text on message CPF1164. Because the message is in the QHST log, users can write application programs to retrieve this data.

Parent topic: Job logs

Related concepts

How job logs are created End of change

Job log pending End of change

Job log server

Job log characteristics

Interactive job logs

Spooled files