Final answer:
In Open ACC for GPU programming, the 'acc wait' directive is used to ensure the synchronization of data structures in a predefined order.
Step-by-step explanation:
When using Open ACC for GPUs and you wish to synchronize the access to a data structure in a predefined order, you should use the acc wait directive. This directive ensures that all preceding asynchronous activities on a specified async queue are complete before proceeding. The acc wait directive can be used with an integer argument to specify the queue. Additionally, using directives like acc update can help manage data transfer between the host and the device to ensure proper synchronization and data integrity.
Learn more about Open ACC Synchronization