XB61 entry for extended buffer list SPAC

Entry:

XB61

VIT option:

XBUF

Event:

Extended buffer list SPAC

VIT processing module:

ISTITCXB

Control is returned to:

INTRACE invoker

This record is produced when VTAM® builds an extended buffer list ShortPAC (SPAC).

The number of trace records required to represent a VTAM internal extended buffer list is based on the number of entries in the structure. The first record in a request is XB61. This record is followed with as many XB62 and XB63 record pairs as is necessary to record the entire VTAM internal extended buffer list contents. The first XB62 and XB63 record pair contains information relating to the extended buffer list control entry. Subsequent XB62 and XB63 record pairs contain information relating to extended buffer list data entries. In addition, if the internal extended buffer list spans more than one SPAC, a new XB61 entry is recorded whenever a new SPAC is used. In this case, the XB61 record contains the previous SPAC address so that the relationship between this record and the previous set of records can be maintained.

The number of trace entries that can be produced has no limit. Although VTAM groups records as a single entity in terms of recording in the trace recording media, there is a finite limit to the number of records that 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 SPAC address is traced in each entry.

Byte (hex)

Contents

00 - 03

Record ID: C"XB61"

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 - 0F

SPAC address

10 - 17

Address of the previous SPAC address, or zeros if this is the first SPAC.

18 - 1B

Return Address

1C - 1F

RPH address