- Entry:
- PIU
- VIT option:
- PIU
- Event:
- PIU record (Part 1)
- VIT processing module:
- ISTRACOT
- Control is returned to:
- ISTLSC6V ISTTSCPR, ISTTSCLS, ISTTSCRI, ISTTSCSC, ISTTSCSR, ISTTSCWS, ISTTSCPD, ISTTSCLE, ISTTSCXS (or ISTINCF1 and INTINCS1 for RUPE)
This trace record provides information about external and internal FID4 PIUs.
For most PIUs, only the first 48 bytes are traced (a 26-byte TH, a 3-byte RH, and the first 19 bytes of RU). However, certain classes of PIUs, such as session control RUs and VTAM® RUs, are traced in their entirety.
If the control block is a RUPE, the TH is reconstructed by the internal trace using what information is available. For TSCB entries, the PIU is recorded as is.
If the PIU is a response with sense data, this entry is
generated whether the PIU option is in effect or not. It is treated
as an exception condition and is always traced if the VIT is active,
regardless of the VIT options specified. 
- Byte (hex)
- Contents
- 00–03
- Record ID: C"PIU"
- 04
- ID is the primary address space ID (ASID). This field is 0 if the ASID is greater than X'FF'.
- 05
- Control block ID: X'54'=RUPE, X'99'=TSCB
- 06-07
- The control block identifier in byte 05 determines the meaning
of this field. TSCB or RUPE information:
- If byte 05 indicates a TSCB, use the following values:
- Byte 06 contains flags (TSCFLAG1).
- Byte 07 contains a unique instance identifier.
- If byte 05 indicates a RUPE, use the following value:
- Bytes 06-07 contain the index for a network element address.
- If byte 05 indicates a TSCB, use the following values:
- 08–0B
- TSCB or RUPE address (see byte 05)
- 0C–1F
- 20 bytes of PIU