gtpi1m36System Installation Support Reference

Deadlock Detection

The deadlock detection user exit, CLUD, is called by segment CL40 with a C function call to perform deadlock notification.

Input

The registers at entry to CLUD are:

R6
Address of both the entry control block (ECB) and the input/output block (IOB) involved in the deadlock condition.

Programming Considerations

This exit provides sample code for a return code of 8.

Return Values

R15 contains the return code:

0
Processing continues as if the exit was never called.

4
Processing ends with an error. The service routine for the ZECBL command (with the E parameter specified) is called to remove all the IOBs associated with this ECB and to schedule a D9 dump.

8
The CE1SUD and CE1SUG fields of each ECB that is involved in the deadlock condition are set to indicate that a deadlock has occurred. The post-interrupt routine in the IOB is also activated.