Trace data buffer

Table 1 and Table 2 define the format of the PIU trace data buffer. This buffer is built by VTAM® and is passed to the user's application program through the ISTPDCLU session established with TRACE in the BIND user data field.

Table 1. PIU trace data buffer header
Byte	Description
0–15	Data routing information
0–1	Binary number representing the total buffer size (in bytes)
2–3	Process identifier
4–7	Data-type identifier
8–15	Reserved
16–25	Buffer eyecatcher = 'NLDM TRACE'
26–27	Buffer sequence number
28–29	Total number of PIU trace data buffer entries
30–35	Reserved
36–47	Access method work area

Table 2. PIU trace data buffer entry
Byte	Bit	Value	Description
0–6			Time stamp (high-order 7 bytes of STCK)
7	0	0	PIU truncated to 40 bytes maximum
		1	PIU is not truncated and requires multiple PIU trace data buffer entries. An integral number of 40-byte trace buffer entries is always used. The size of the PIU can be calculated using the data count field in the TH of the PIU.
	1-7		Buffer entry type: X'00' Normal PIU X'01' Normal PIU — inbound X'02' Normal PIU — outbound X'03' Access method specified symptom string X'04' Discard PIU — session active X'05' Discard PIU — session inactive X'06' Internally generated PIU
8–47			Trace data