Using Space Recovery software with XCOM for z/OS NOTE/POINT processing

Products

• XCOM Data Transport - z/OS

Issue/Introduction

Space Recovery System (SRS) software will attempt to make a dataset multi-volume to help with out of space (B37) type conditions.

Out of space is a big problem with file transfers for various reasons.

SRS cannot help with datasets being written to by XCOM because of XCOM's use of NOTE - I think this is a DCB attribute that allows knowledge of where you are in a file that you're writing to. Maybe required for checkpointing?

Is there an XCOM option that can be turned off to allow SRS to do it's thing.

Environment

XCOM™ Data Transport® for z/OS

Resolution

In summary third-party Space Recovery software products like SRS are NOT compatible with XCOM. 

The primary reason is that they overlay XCOM's DCB abend exit. That is how their code gets control in the event of an x37 abend so that it can adjust the space allocations of the subject datasets.
This limitation is documented here: XCOM™ Data Transport® for z/OS 12.0 > Administrating > How to Use Your Product with Other Products > DCB ABEND Exit Software

Beyond that, XCOM checkpoint/restart is architected around NOTE/POINT processing. Disabling checkpointing by specifying CKPT=0 simply causes XCOM to not exchange file positions with the remote partner at regular intervals during a transfer. However XCOM still makes use of NOTE macros internally at the beginning and end of every transfer.