Advanced Topics › TPCF Device Processing › Unexpected Results in Device Allocation

Unexpected Results in Device Allocation

Sometimes device allocation for a job does not produce expected results. It may be that a job goes into allocation recovery when it appears that online devices are available. Or a job may select an unexpected device for allocation or not select an expected device. Most of the time, the unexpected results are due to the elimination or preferencing applied to the devices. The final selection of devices of z/OS is a combination of all the elimination and preference logic performed by z/OS and other vendor software.

For example, robotic software, TPCF (job reserve, TPCEDLXT exit, and so on), or both may eliminate all available online devices, sending a job into allocation recovery, when it appears online devices are available. When a job gets unexpected results in device allocation, examine the elimination and preferencing affecting the devices in the EDL of the job. Are the devices inside or outside a robot? Are they ACL devices? Are any devices reserved?

TPCF provides tracing through the DEVSEL24, DEVSEL78, and RECOVERY parameters of the SETOPTION TPCF SETTRACE and SETPRINT commands that assist in diagnosing device selection and allocation recovery problems.