Use of XCOM EXIT07 to Enforce Site Standards for XCOM for z/OS

Products

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

Issue/Introduction

How to use XCOM EXIT 07 beyond its documented functionality to enforce site standards related to XCOM.

 

 

Environment

XCOM™ Data Transport® for z/OS 12.0

Resolution

The User guide documents that exit 07 can be used to either accept or reject a transfer request by setting a return code in the parameter list that xcom passes to it.

However, since that parameter list contains pointers to the actual XCOM control blocks, it means that the exit has the ability to update them.

In particular, the exit can modify the parameters of any locally initiated transfer, either submitted via batch, ISPF interface or the XCOM API. This is because all these ways to initiate a transfer result in execution of the XCOMJOB program, which calls exit 07 as part of its processing.

When the exit is called, XCOMJOB has parsed the statements entered in SYSIN01 and has built a transfer request ready to be processed or sent to the started task for processing. The transfer request information is stored in RRDDSECT DSECT, which is pointed to by field EX07RRD in the EX07PLIST DSECT that the exit receives as parameter.

If the exit updates any transfer parameter stored in RRDDSECT it has the same effect as if the value had been entered via SYSIN01 DD

For example, the exit might force a default for XCOM compression. The default for SYSIN01 parameter COMPRESS is YES, but an exit 07 can change it by updating field RRDCOMPF.

Both EX07PLIST, RRDDSECT and HDRDSECT (which is used by RRDDSECT) members can be found in the XCOM macro library (CAI.CBXGMAC). There is a sample exit 07 available in member XCOMEX07 in the CAI.CBXGSAMP(XCOMEX07)  library. 

Additional Information

Link to documentation. EXIT07