- Entry:
- XBA1
- VIT option:
- XBUF
- Event:
- OPTCD=XBUFLST request on APPCCMD macroinstruction
- VIT processing module:
- ISTITCXB
- Control is returned to:
- ISTPSCFM, ISTPSCFR, ISTPSCFS, or ISTPSCMU
The XBA1 record is created by any of the following conditions:
- An HPDT send is issued (send request with OPTCD=XBUFLST specified).
- An HPDT send is completed and RPLXSRV is not set.
- An HPDT receive (APPCCMD CONTROL=RECEIVE with OPTCD=XBUFLST) is completed.
The entry contains information required to correlate this set of extended buffer list entries to an appropriate APPC entry (either ACA1 or ACP1/ACR1).
The number of trace records required to represent an application request buffer list is variable based on the number of entries present in the buffer list.
The first record in a request is XBA1. This record is followed with as many XBA2 and XBA3 record pairs as is necessary to record the entire application buffer list contents.
There is no limit to the number of trace entries that
can be produced. Although VTAM® groups
records together as a single entity in terms of recording in the trace
recording media, there is a finite limit to how many records can be
written externally or recorded internally at one time. Because of
multiprocessing, other VIT records from unrelated operations can be
interleaved in the trace output between the XBUF entries for a given
operation. To provide correlation between groups of XBUF entries,
the RPL address is traced in each entry. 
- Byte (hex)
- Contents
- 00–03
- Record ID: C"XBA1"
- 04
- ID is the primary address space ID (ASID). This field is 0 if the ASID is greater than X'FF'.
- 05–07
- 0
- 08–0B
- RPL address. This field corresponds to the RPL address of the ACA1, ACP1, or ACR1 entry.
- 0C–1B
- 0
- 1C–1F
- RPH address