CURRENT SERVER special register
The CURRENT SERVER (or CURRENT_SERVER) special register specifies a VARCHAR(18) value that identifies the current database server (sometimes referred to as the application server). The register contains the actual name of the database, not an alias.
CURRENT SERVER can be changed through the CONNECT statement, but only under certain conditions.
When used in an SQL statement inside a routine, CURRENT SERVER is not inherited from the invoking statement.
Example: Set the host variable APPL_SERVE (VARCHAR(18)) to the name of the database server to which the application is connected.
VALUES CURRENT SERVER INTO :APPL_SERVE