Log Dataset

The Strobe log dataset contains an historical record of all activity initiated through the session manager. It can help you track the activity and the history of individual requests. The log also provides a valuable record in the event of problems with Strobe.

All messages in the log dataset begin with the date and time, the MVS system name, the job name of the issuer of the Strobe operation, and, when available, the request number and job name associated with the request.

Log Dataset Characteristics

The log dataset is a sequential dataset that must reside on a direct access device. The DCB specifies a record format of VBA. The record length is 137. The block size can range from 141 to the maximum size for the device (default 3024). If you do not want to use the defaults, specify the block size when you allocate the dataset. (Always select a moderate block size, because large block sizes result in wasted space.) A primary allocation of 10 tracks with a 10-track secondary allocation is sufficient for most installations.

The log dataset is always allocated with a disposition of share to allow multiple users of Strobe to be active at the same time. It should never reside on a system pack.

When Strobe creates its environment, it acquires the dataset name of the log from the SYSLOG data definition statement supplied in the startup procedure.

For an example of the log dataset, see the Strobe SAMPLIB member $07ALSTR.

Warning

Do not rename or reallocate the log dataset while the Strobe environment is active. Strobe uses the dataset name for all subsequent invocations.

Managing the Strobe Log Dataset

Strobe cannot execute when the log dataset is full. To make sure that space is available, issue the SHOW LOG command to display the status of the log.

You can issue this command through the MVS system MODIFY command on the operators console:

   MODIFY STRxSM,SHOW LOG

or through Strobe/ISPF:

   .SHOW LOG

Strobe displays the following status information:

  • Name of the log dataset
  • Percentage of space used
  • DCB characteristics
  • Space allocation
  • Number of extents.

If the log dataset belongs to a GDG, Strobe displays the following information for each dataset in the group (to a limit of ten):

  • Name of the log dataset
  • Date and time Strobe allocated the dataset.

Managing a GDG Log Dataset

When you install Strobe with a log dataset that belongs to a GDG, Strobe takes care of the maintenance. It dynamically allocates a new generation of the log dataset when the current generation reaches the threshold set by the LOG_MAX value in the PARMLIB member. You rarely need do anything else to make sure the log dataset is available.

Use the LOGSWITCH command to force the allocation of a new generation before the current log dataset is full. Submit the command with the start of the session manager or as a command through the operator’s console. From an operator’s console, enter:

   MODIFY STRxSM,LOGSWITCH

Strobe closes the current dataset and allocates a new one with a higher generation number.

Warning

To manage GDG log datasets, use only the LOGSWITCH command. Do not use the LOGCLEAR command.

When Strobe allocates a new log dataset automatically or through a LOGSWITCH command, it applies the following values from the PARMLIB member:

  • LOG_SPACE
  • LOG_UNIT
  • LOG_VOL

If these values are not in the PARMLIB member, Strobe uses the allocation information from the current in-use log. Other characteristics for newly allocated datasets are determined by Automatic Class Selection (ACS) code that is written by the system administrator at your site. The session manager supports allocations in blocks, tracks, or cylinders.

Managing a Non-GDG Log Dataset

Strobe helps you manage the log when you have not defined it to a GDG. The session manager sends a warning message to the operator’s master console when the log dataset exceeds 80% of the space allocation. Strobe sends an additional message each time the log dataset exceeds 80% of the space allocation. When the log fills, Strobe issues a message with each attempt to write to the log.

For example, Strobe sends a warning message at the following intervals:

  • When the log dataset exceeds 80% full
  • When the log dataset exceeds 85%, 90%, and 95% full
  • Each time Strobe attempts to write to the log after it fills.

Based on these messages, you can modify your automated facility for handling console messages to schedule the execution of the Strobe utilities for managing the log dataset.

Strobe provides a command (LOGCLEAR) and a utility program (STRBCLOG) to manage non-GDG log datasets.

Using the LOGCLEAR Command

Use the LOGCLEAR command to clear and reuse the log dataset, as follows:

   MODIFY STRxSM,LOGCLEAR

Submit the command with the start of the session manager or as a command through the operator’s console. Strobe does not preserve the original contents of the log.

Warning

Use the LOGCLEAR command only for non-GDG log datasets. Do not use the LOGSWITCH command.

Using the Strobe Log Utility Program

To copy the log to a backup dataset and clear the log, submit the Strobe Log Utility program from your unauthorized Strobe load library. The utility enqueues exclusively on the log resource, so that Strobe cannot write to the log when it is being cleared. The STRBCLOG program (Copying the Log to a Backup Dataset (Member STRBCLOG)) copies all DCB characteristics from the current log and accepts overrides on the DD statement for BLKSIZE to allow for efficient blocksizes on the backup.

Copying the Log to a Backup Dataset (Member STRBCLOG)

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