MAXPACK=1023000 causes errors XCOMU0492E & XCOMM0153E

Products

• XCOM Data Transport - z/OS
• XCOM Data Transport - Linux PC
• XCOM Data Transport

Issue/Introduction

Recently implemented new level of XCOM with LU05222, and received errors XCOMU0492E & XCOMM0153E from 2 servers.
For XCOMM0153E compression was turned off and the problem resolved.
For XCOMU0492E MAXPACK was reverted to 31744 and the problem resolved.

Environment

Release : 12.0

Component : XCOM Data Transport for z/OS

Resolution

XCOMU0492E:
The XCOM version which returned XCOMU0492E "MAXRECLEN exceeds limit for record packing" is XCOM for Linux r11.6 SP01 17021. That version supports a maximum of 31KB pack buffers and thus when MAXPACK was reduced to 31744 the transfer was successful. However from one of the fixes listed in XCOM for z/OS patch LU05222 ('USE "X" AS INTERNAL PACK FLAG FOR MAXPACK > 31744'), it might have been expected that XCOM for z/OS would have automatically negotiated down to the lower MAXPACK value that the remote XCOM could support and prevented the XCOMU0492E error from occurring.
For this scenario using MAXPACK=31744 was an acceptable workaround because there was currently no driver for needing to use a larger MAXPACK value.

XCOMM0153E:
The XCOM version which returned error XCOMM0153E "INVALID DATA RECEIVED -- EXPECTING FMH7 AFTER RC 0846" is XCOM for Windows 11.6 SP01.
XCOMM0153E is a response to an error that occurred on the remote partner system. It may be that the Windows side is generating the equivalent error to above for Linux i.e. XCOMN0492E
Similarly for this scenario having compression disabled was an acceptable workaround 

Additional Information

If such errors are seen first confirm if XCOM for z/OS patch LU05222 is already installed.

1. If LU05222 is not installed apply it and retest the problems.
2. If LU05222 is installed and the errors still occur then if similar workarounds are not acceptable please capture the following diagnostics and create a support case for XCOM Support/Engineering to research further:
   1. The SYSIN01 used to reproduce the problem.
   2. The DCB info of the file trying to be sent to the remote server.
   3. Traces need to be enabled and captured from both the z/OS and remote server sides.
   4. For z/OS please see KB article: https://knowledge.broadcom.com/external/article/15147 .For Linux or Windows in the XCOM_HOME/config/xcom.glb file the parameter XTRACE will need to be set to a value of 10 and the xcomd daemon/service restarted. The trace files will be created in directory XCOM_HOME/trace. After successful capture revert the XTRACE setting to 0 and again restart the xcomd daemon/service.
   5. On z/OS the complete output of the transfer and on Linux/Windows copies of files XCOM_HOME/config/xcom.glb & XCOM_HOME/xcom.log.