Externalizing trace data in a dump

You can externalize your trace data in the following types of dumps:

SVC dump
Summary dump
Stand-alone dump.

You can obtain both an SVC dump and a summary dump through the SDUMPX macro. You can obtain a stand-alone dump by asking the operator to request one for you.

Obtaining SVC and summary dumps: To obtain SVC and summary dumps, use the SDUMPX macro to dump the storage containing:

The trace buffers
Any control information needed by the CTRACE buffer find exit routine to locate the trace data.

Note: You must specify SDATA=(SQA) on the SDUMPX macro to dump the necessary component trace control information.

If tracing continues while the trace buffers are being dumped, the application can take either of the following steps to ensure useful data in the dump:

Make the trace buffers large enough so the trace data does not wrap around.
Suspend tracing until the trace buffers are dumped.

When you use SDUMPX to request an SVC dump, you also get a summary dump by default. Summary dumps can contain up to 4 megabytes (4MB) of data, so the application might plan on receiving about 3.5MB of trace data. If your trace buffers are much larger than 3.5MB, consider suppressing the summary dump and externalizing the trace data through the SVC dump only.

Obtaining a stand-alone dump: To include the trace buffers in any stand-alone dumps, ask the operator to dump the storage containing the trace buffers. You must do one of the following:

Ensure that the trace buffers and control information are in storage that will always be dumped by the stand-alone dump program (SADMP).
Set up the SADMP program to specifically dump the desired areas.
Have the operator specify storage ranges on the prompt from SADMP.
See z/OS MVS Diagnosis: Tools and Service Aids for information about the stand-alone dump program (SADMP).

Many components can locate their CTRACE buffers in a dump without the USERDATA supplied by a CTRACE DEFINE operation. IBM® advises such components to supply a CTRACE parmlib statement during IPCS session initialization. This allows the CTRACE subcommand to associate the name of the component with the name of the format table supplied by the component. In turn, this permits the component CTRACE buffers to be located and processed regardless of whether a dump contains SDATA=(SQA) information, which is the traditional way that the CTRACE subcommand determines the name of the format table for a component.