When pinning is required

A UCB must be pinned in the following environments:
  • The device represented by the UCB is offline and unallocated, but a program might still require access to the UCB and its related control block structures.
    Note: For a dynamic device to be deleted, it must be offline and unallocated, and its UCB must not be pinned. When a device is in the offline and unallocated state, the only way for a program to prohibit the deletion of the device is to pin the UCB for the device.
  • The device represented by the UCB can become offline or unallocated while the program is accessing it.
  • The UCB address is passed between programs that are running asynchronously.
Parent topic: Ensuring that UCBs are not deleted