The CLOSE macro instruction restores one or more data control blocks so that processing of their associated data sets can be terminated. Issue CLOSE for all data sets used by the direct access channel program. When CLOSE is executed, some of the following procedures are performed:

• Releasing the data extent block
• Removing information that was transferred to data-control block fields when OPEN was executed
• Verifying or creating standard labels
• Releasing programmer-written appendage routines.