XCOM - Huge record packing (MAXPACK greater than 31K) support by non-Z/OS partners
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XCOM - Huge record packing (MAXPACK greater than 31K) support by non-Z/OS partners


Article ID: 236710


Updated On:


XCOM Data Transport - z/OS


In XCOM for Z/OS at release 12.0, fix SO09365 introduced an enhancement to the record packing feature which increased the maximum buffer size (specified in parameter MAXPACK) from 31K to 1M (up to MAXPACK=1023000)

Is it possible to use this enhancement when transferring to non-Z/OS platforms?


Release : 12.0

Component : XCOM Data Transport for z/OS


This enhancement is supported by Windows and Unix/Linux partners as follows:

  • XCOM for Windows supports it starting at release 11.6 SP03
  • For Unix/Linux platforms, this feature is planned for release 12.0
  • In both cases, the maximum buffer size supported by XCOM in Windows/Unix/Linux is 64K
  • Regardless of the above, the Z/OS partner may specify the maximum value for MAXPACK and the actual buffer size to be used will be negotiated with the partner and lowered as needed during transfer initialization.


Additional Information

Under the covers, this enhancement introduces a new type of record packing in the control block that is sent to the partner with the requested transfer parameters (also known as "XCOM header"). This change requires logic to be added to the partners in order to recognize the new record packing type.

When the partner does not support that new type of record packing, it issues an error about "unsupported record packing type"