If lob-locator was retrieved inside an iteration macro or function (that is, one of map-query, do-query, simple-do-query andloop), it is freed before the next record is fetched, or when terminating the iteration for the last record.
LOB locators which were retrieved by select or query, or were created by the user by ora-lob-assign or ora-lob-create-empty are freed automatically when the database connection is closed by a call to disconnect.
ora-lob-free is available only when the "oracle" module is loaded. See the section Oracle LOB interface for more information.
LispWorks User Guide and Reference Manual - 20 Sep 2017