CTnBPXxx

The CTnBPXxx member of SYS1.PARMLIB is used to control tracing. It specifies the tracing options for a component trace of z/OS UNIX events.

One member should control initial tracing, which automatically starts when the OMVS address space is started. It should store trace records in a buffer, which could be read if a dump is written. This member should be considered the operating system's default member.
The CTRACE parameter in the BPXPRMxx member specifies the member; see Figure 1, where CTIBPX00 is specified.
One member can be set up to trace all z/OS UNIX events. This member is CTIBPX01. This method enables a site to change trace information on the fly to obtain suitable component trace information for a dump. (CTIBPX00 traces minimum information.)
Create other members as needed or when requested by the IBM® Support Center.

To change the tracing to collect data needed for a particular problem, ask the operator to enter a TRACE CT command that specifies a different, customized CTnBPXxx member that you have placed in parmlib. When you want to resume normal tracing operations, enter another TRACE CT command specifying the normal CTIBPXxx that your installation uses.

Figure 1 shows the IBM-supplied CTIBPX00 member in SYS1.PARMLIB.

Figure 1. CTIBPX00 member of SYS1.PARMLIB

TRACEOPTS
          ON
          BUFSIZE(128K)
/*        OPTIONS(             */
/*                'ALL     '   */
/*               ,'CHARS   '   */
/*               ,'DEVPTY  '   */
/*               ,'FILE    '   */
/*               ,'LOCK    '   */
/*               ,'PIPE    '   */
/*               ,'PROCESS '   */
/*               ,'PTRACE  '   */
/*               ,'SIGNAL  '   */
/*               ,'STK     '   */
/*               ,'STORAGE '   */
/*               ,'SYSCALL '   */
/*               ,'DEVRTY  '   */
/*               ,'IPC     '   */
/*               ,'XCF     '   */
/*                )            */

The statements in CTIBPX00 do the following:

ON turns on the tracing.
BUFSIZE sets the buffer size at 128KB.

You can specify a buffer size between 16KB and 64MB on the BUFSIZE statement. Use the TRACE CT operator command to change the size of the trace buffer.

Use any of the listed options to specify which events can be traced. For performance reasons, set component tracing off during normal operations. With CTRACE set to OFF, minimal tracing is done.

Customize tracing by adding CTnBPXxx members and storing them in SYS1.PARMLIB. In these members, anticipate events to be traced for diagnosis. The initial CTIBPX00 member specifies minimal tracing. The TRACE CT operator command specifies the customized member name.

Figure 2 shows a member, CTCBPX08, with an OPTIONS statement that requests tracing of events in files and pipes.

Figure 2. Customized CTCBPX08 parmlib member

TRACEOPTS
WTRSTART(CTWTR)
ON
BUFSIZE(4M)
OPTIONS('FILE','PIPE')
WTR(CTWTR)

The WTRSTART statement specifies a CTWTR cataloged procedure, which the installation wrote and which starts a component trace external writer. The buffer size is set at 4M.

When re-creating a problem for IBM service, you should increase the buffer size to its maximum.