The following values are provided as RETURN-CODE values from the thread-specific data handling routines:
| 0 | No error was encountered. |
| 1000 | Memory allocation error. |
| 1001 | Thread-storage handle is invalid. No operations are valid on this thread-storage handle. It is possible that the handle specified was once valid but it has been closed and the memory reused. |
| 1002 | Thread-storage handle is invalid. The thread storage handle has previously been closed and is no longer valid. |
| 1009 | Invalid parameter passed into a thread-specific data-handling library routine. A parameter has been detected as being out of valid ranges or inconsistent with the library routine. |
| 1010 | Resource busy. A synchronization object was still locked upon thread termination and when the thread was created the user requested an error to be reported if this condition occurred. |