LINC Programming Reference Manual - Public Support Login - Unisys

SWITCH.TO (SWT)
Host LINC implementation of SWITCH.TO; assumes the disengagement of one LINC
System and the engagement of another, and does not involve the shutdown of either
system. The LDA implementation cannot avoid closing down one system before
engaging the other. Therefore, it cannot be assumed that STARTUP logic has been
executed in LDA.
Runtime Requirements
For an MCP based LINC System
To use this command on MCP based target hosts, you must install a COMS processing
item, such as TPTOMARC, for the MARCINPUT agenda. For more details, see your MCP
Based LINC Installation and Configuration Guide.
If you switch to an invalid system name, your originating screen is displayed. A message
informs you that the system you were attempting to switch to is not available.
For an OS 2200 based LINC System
You can use this command to switch to another LINC System. If you are switching from a
System running with PowerClient, and the other LINC System is not generated for use with
PowerClient, the SWITCH.TO; command will fail and you will be signed off.
For a UNIX LINC System
Define the environment variables database_DIR and database_ENV. These variables can
be defined for each user, for all users of a LINC System, or for all users. See your UNIX
LINC Administration and Operations Guide for details of environment variables.
If you attempt to switch to an invalid system name, you will be returned to your originating
screen if you switch without a BYE command, or logged off if you switch with a BYE
command. A message is displayed informing you of the unavailability of the system you
were attempting to switch to.
Runtime Transaction Flow
The effects of using the SWITCH.TO; command on transaction flow are as follows.
$ The SWITCH.TO; command takes effect at the end of the Ispec Logic. This is similar to
the RECALL; command.
$ On execution of the command, GLB.ERROR is set to five asterisks (*****).
$ All logic following the SWITCH.TO; command is processed.
$ If multiple SWITCH.TO; and RECALL; commands are executed in the same Ispec, only
the last SWITCH.TO; or RECALL; command executed is actioned.
$ GLI, OFFLINE, external Automatic Entry (HUB), and OLTP transactions ignore this
command.
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