To gain the right to view or update the object, an application must use the ACCESS service. You normally invoke ACCESS after you invoke IDENTIFY and before you invoke MAP. ACCESS is similar to the OPEN macro of VSAM. It has a mode parameter of READ or UPDATE, and it gives your application the right to read or update the object.
If the object is a data set and if the SHAREOPTIONS parameter used to allocate the linear data set implies serialization, the system automatically serializes your access to the object. If access is not automatically serialized, you can serialize access to the object by using the ENQ, DEQ, and the RESERVE macros. If you do not serialize access to the object, you should consider using the LOCVIEW parameter to protect your window data against the unexpected changes that can occur when access to the object is not serialized. LOCVIEW is described under the topic The ACCESS service.
If the object is a hiperspace, DIV ensures that only one program can write to the object and that multiple users can only read the object. Only the task that owns the corresponding ID can issue ACCESS.