Sense code 800A0000 or no message, and sessions end unexpectedly

Problem statement

A session ended unexpectedly and either no message is received or an exception request (EXR) with a sense code of 800A0000 flows to the destination LU.

Common symptoms

Upon receiving the sense code 800A0000, the LU might return the code in a response. Some LUs will include the code in an UNBIND.

Probable cause

If a path information unit (PIU) is too large to be passed from one PU type 4 or type 5 to another, an exception request (EXR), containing sense code 800A0000 and up to 3 bytes of the RU, may be generated. See Table 1 to determine what document describes the building of the EXR.

User response

For VTAM® and NCP nodes in the session path, check the following definition values for each configuration used:

VTAM to channel-attached NCP: VTAM will take the smaller of the following two values:
- MAXDATA value on the PCCU definition statement (or on the LINE definition statement for a channel-attached NCP).
- Value sent in the XID of the maximum PIU size for the NCP. This number will be the product of the BFRS value from the BUILD definition statement and the TRANSFER value from the channel adapter LINE definition statement for 3745 or 3720 with V5 NCP or from the BUILD definition statement for other NCPs.
Channel-attached NCP to VTAM: The product of the MAXBFRU value from the HOST definition statement (or from the LINE definition statement for a channel-attached NCP) and the IOBUF size from the VTAM start options. This value will be the maximum size that can flow from the NCP to the host.
VTAM-to-VTAM connection across a channel-to-channel interface:
- If both VTAMs have the CTCA enhancement: The product of the MAXBFRU value from the CTCA LINE definition statement and the IOBUF size from the VTAM start options.
- If one or neither of the VTAMs has the CTCA enhancement: The product of the MAXBFRU value from the LINE macro and the IOBUF size from the VTAM start options.
NCP to link-attached NCP: The product of the TRANSFR value on the LINE definition statement and the BFRS value on the BUILD definition statement.
NCP to link-attached VTAM: The product of the MAXBFRU value from the CA LINE definition statement and the IOBUF size from the VTAM start options.

Note:

The definition statements for all PU type 4 or type 5 nodes on the session path must be checked, because any PU type 4 or type 5 can change the PIU into an 800A0000 exception request.
The information in this problem description is from information APAR II03990.