SYSGEN is a utility used to modify the system configuration.
System configuration changes are kept to disk in a configuration
group or to a tape called a system load tape (SLT). The SYSGEN utility
requires system supervisor (OP) capability to view system configuration
and system manager (SM) capability to save changes or create an SLT.
SYSGEN contains a global module and four configurators:
Input/Output (IO) Configurator. Configures the local devices
for the target system.
Logging (LOG) Configurator. Changes the attributes of the
user logging and system logging processes.
Miscellaneous (MISC) Configurator. Focuses on system limits
and startup values, especially those related to jobs, sessions, and
processes.
System File (SYSFILE) Configurator. Changes the list of
files dumped to an SLT.
Each configurator provides an interface to make changes to
an independent portion of the configuration data and offers a menu
of commands and online syntax help. Command names and abbreviations
are easily identified. For example, the command to add a device
is ADEV (abbreviated AD), while the command to delete a device
is DDEV (abbreviated DD).
The configurators operate on information contained in the
base configuration group. This basegroup is the group used to begin
making changes to the system configuration. The basegroup includes
a permanent set of configuration files that contain information
on device classes, assigned I/O paths, assigned logical device (LDEV)
numbers, current volume names, and various other system parameters.
Activating SYSGEN creates a set of temporary configuration
files that correspond to the permanent file set specified with the BASEGROUP
command. Configuration changes are made to the temporary
configuration files. Once the changes are complete, the system manager
uses the KEEP command to overwrite the permanent file set with the
temporary file set or to save the temporary files to another permanent
file set.
When KEEP is used to save changes to a new group name, SYSGEN stores
the modified base group files in a group in the SYS account. The changes
take effect once the system
is rebooted with START NORECOVERY.
SYSGEN also provides a CLEAR command to erase changes made through
one or more of the configurators.
NOTE: When SYSGEN generates a boot tape, it writes the current
configuration data as the group CONFIG.SYS, regardless of the group name
on disk. CONFIG is the group selected by default by the START
utility and used to start a system. For more information on the
START utility, refer to Chapter 3 System Startup Functions
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