Message IST259I received with INOP RU

Problem statement

Message IST259I is generated by the inoperative (INOP) RU processor. The INOP RU is generated by the data link control (DLC) component for the subarea controlling the link, either intermediate network node (INN) or route extension (REX).

Common symptoms

The following message is displayed:

IST259I  INOP RECEIVED FOR nodename CODE = code

If the link is INN, an ER.INOP will also flow, producing a series of explicit route (ER) or virtual route (VR) failure messages. This leads to an incorrect diagnosis when you do not associate the ER.INOP with the link or link station INOP.

If message IST259I contains the name of a channel-attached NCP or a local device, message IOS000I might accompany the failure.

If message IST259I contains the name of a channel-attached 3172 device, messages IST1411I, IST1412I, or IST1430I will indicate the reason for the INOP. For more information, see z/OS Communications Server: SNA Messages.

Some local SNA controllers require I/O buffer size to be an even number. For example, if an odd number is coded for a 3174, message IST259I with CODE=01 will be displayed at activation.

Probable Cause

NCP link: This is a communication facility problem. Either the retry limit is exhausted, a negative acknowledgment is received for an SDLC transmission, a modem error occurred, or a link failure occurred.
Channel link: Either a data transfer count mismatch occurred, an NCP abend has occurred, or the NCP was reloaded by another host.

User Response

Trace the link.

List the system LOGREC to obtain the data from the record management statistics (RECMS) that accompany an INOP originating in an NCP node. The RECMS identifies the error that produced the INOP. Use environmental record editing and printing (EREP) to print the LOGREC records. Use the network problem determination application (NPDA) to interpret the RECMS record.

VTAM® does not generate the RECMS for channel link and link station failures. The LOGREC entry for a local device will contain only statistical data.

Correct the error condition.

Note: The IBM® Support Center representative can only suggest that you list LOGREC and assist you with interpreting the record.

If a channel-attached SNA device (NCP or cluster controller) is experiencing the INOPs at a regular or predictable interval (for example, every hour), the problem could be that the VTAM ERP routine has been deleted. Verify that CSECT ISTZBM0K in load module IGE0004 (LPALIB) has not been deleted.