CSS line trace

The CSS line trace records information from the data exchanged between NCP and the 3746 Model 900 and from the data in the following interface control blocks:

  • CSS-processor-to-NCP dynamic parameter status area (LDPSA)
  • CSS-processor-to-NCP parameter status area (LPSA)
  • NCP-to-CSS-processor dynamic parameter status area (NDPSA)
  • NCP-to-CSS-processor parameter status area (NPSA)

See CSS line trace report (CSPRT) for a sample ACF/TAP report.

Figure 1 shows the relationship of the connectivity subsystem line trace to NCP and to the hardware. It also shows the CSS adapter trace trace-point sources. For more information, see CSS adapter trace.

Figure 1. Relationship of the CSS line trace to NCP and to the 3746 Model 900 hardware
Relationship of the CSS line trace to NCP and to the 3746 Model 900 hardware

Activate and deactivate this trace from the VTAM® console as a LINE.

You can request a trace of a logical or physical line. Physical line trace data includes commands for the physical line and for the associated logical lines. Logical line trace data includes only commands and associated data directed to logical resources for that line.

For integrated services digital network (ISDN), you can request a trace of a logical, B-channel, or physical line. Physical line trace data includes commands for the physical line, the associated B-channel lines, and the associated logical lines. B-channel line trace data includes commands for the B-channel line and the associated logical lines. Logical line trace data includes only commands for the logical line.

Before V7R5, a high-speed line trace can be activated only when no other line traces (high-speed or low-speed) are active. 3746 Model 900 lines that are considered high speed are the following:

  • Logical and physical Enterprise systems connection (ESCON) or token-ring lines
  • SDLC, frame-relay, or X.25 lines with SPEED=1048576 or greater on the LINE definition statement
  • A logical frame-relay line that does not have the SPEED keyword coded but has an associated physical line that is coded with SPEED=1048576 or greater.

Starting with V7R5, you can activate more than one CSS line trace even when a line trace is active for a high-speed line. The number of line traces that can be active at one time is limited by the LTRACE keyword on the BUILD statement, which has the maximum value 8.

For high-speed 3746 Model 900 lines, the amount of data to be traced for receive and transmit PIUs is limited to a maximum of 40 bytes. Starting with V7R5, the amount of data to be traced for the 3746 Model 900 lines is unlimited.

For the layout descriptions of the interface control blocks shown in the CSS line trace, see the NCP and EP Reference Summary and Data Areas, LY43-0030.