Each component determines the buffer size and how it is specified. Depending on the component, you may or may not be able to change the buffer size. You may be able to change the size only at system or component initialization, or when the trace is started, or at any time, including while the trace is running. Table 1 shows how the buffers specifications.
The buffer size determines whether you get all the records needed for diagnosis; when the buffer is full, the system wraps the buffer, overwriting the oldest records. To change the size of the buffer, specify an nnnnK or nnnnM parameter on the TRACE CT operator command or a BUFSIZE parameter in the parmlib member.
Usually you should increase the size of the trace buffer when you increase the amount of tracing. However, if you plan to place a component's trace records in a trace data set, you can probably leave the buffer at its original size. Many component traces do not allow you to change the buffer size after initialization; the table indicates those component traces. If you increase the amount of tracing for one of these traces, specify use of a trace data set, if the component supports its use.
| Trace | Default size and size range | Size set by | Change size after IPL | Buffer location |
|---|---|---|---|---|
| SYSAPPC | 512KB 64KB - 32MB |
CTnAPPxx member or REPLY for TRACE CT command | Yes, while a trace is running | Data space. A TRACE CT,OFF command requests a dump, which includes the trace buffers |
| SYSAXR | 2MB 1MB - 2GB |
CTIAXRnn parmlib member or REPLY to TRACE CT command | Yes, when restarting a trace after stopping it | AXR private; AXR trace dataspace |
| SYSBCPII | 4M 4M |
MVS™ system | No |  Data space. A SLIP or DUMP
command can always be issued to capture the trace buffers for the
BCPii address space. (Specify ASID=(BCPii's ASID),DSPNAME= ('HWIBCPII'.*))
In addition, if CTrace for SYSBCPII is ON, a Trace CT,OFF command
requests a dump, which includes the trace buffers. |
| SYSBHI |
4MB 4MB - 64MB |
CTIBHIxx parmlib member or REPLY to TRACE CT
command |
Yes, while trace is running |
64-bit Common Service Area (ECSA) |
| SYSCEA | 2MB 1MB - 2GB |
CTICEAnn parmlib member or REPLY to TRACE CT command | Yes, when restarting a trace after stopping it | CEA private; CEA trace dataspace |
| SYSDLF | N/A | MVS system | No | Data space. In the REPLY for the DUMP command, specify DSPNAME= ('DLF'.CCOFGSDO) |
| SYSDSOM | N/A | MVS system | No | Private address space |
| SYSGRS | 16M 128KB - 2047MB (System rounds size up to nearest 64KB boundary.) |
CTnGRSxx member | Yes. | In the GRS address space above the bar which means it will not constrain GRS virtual storage. Options such as FLOW, REQUEST, and MONITOR produce a large number of entries in a short period of time. When dumping by SDUMP, specify ASID=GRS's asid and SDATA=(RGN,NUC). The RGN is needed for blocks that address the ctrace buffer. Note that SDATA=GRSQ does not collect GRS CTRACE. |
| SYSIEFAL | 4M 256KB - 8MB |
CTIIEFxx member | Yes. | In the component address space |
| SYSIOS | 324KB 324KB-1.5MB |
CTnIOSxx member or REPLY for TRACE CT command | Yes | Extended system queue area (ESQA). Note: Full
buffers are copied to an IOS data space to allow for more data capture.
For information about specifying an IOS data space size at IPL, see
OPTIONS parameter.
|
| SYSJES | N/A | MVS system | No | In the component address space |
| SYSjes2 | N/A | JES2 | No | In the component address space |
| SYSLLA | N/A | MVS system | No | In the component address space |
| SYSLOGR | 2MB 2MB - 2047MB |
MVS system, CTnLOGxx member, or REPLY for TRACE CT command. | Yes | Data space. In the REPLY for the DUMP command, specify DSPNAME= ('IXLOGR'.*). See Obtaining a dump of system logger information. |
| SYSOMVS | 4MB 16KB - 64MB |
CTxBPXxx member or REPLY for TRACE CT command | Yes, when initializing z/OS® UNIX. | Data space. In the REPLY for the DUMP command, specify DSPNAME= (asid.SYSZBPX2) where asid is the ASID for z/OS UNIX. |
| SYSOPS | 2M 64KB - 16MB |
CTnOPSxx member or REPLY for TRACE CT command | Yes, when restarting a trace after stopping it | Console address space (private). |
| SYSRRS | 1MB 1MB - 2045MB |
CTxRRSxx member or REPLY for TRACE CT command | Yes, when restarting a trace after stopping it | Data space and component address space. In the REPLY for the DUMP command, specify DSPNAME=('RRS' .ATRTRACE) and SDATA=RGN. |
| SYSRSM | 3 buffers of 132 pages 2 - 7 page-fixed 1 - 2047 MB for |
CTnRSMxx member or REPLY for TRACE CT command | Yes, when starting a trace | Common service area (LIKECSA) or, if specified in CTnRSMxx, high virtual private storage of the RASP address space. |
| SYSSPI | 64KB | MVS system | Yes, when starting a trace | In the component address space |
| SYSTTRC | 1 MB 16K - 999K 1MB - 32MB |
MVS system | Yes | Data space owned by the system trace address space |
| SYSVLF | N/A | MVS system | No | Data space. Enter DISPLAY J,VLF to identify the VLF data spaces. In the REPLY for the DUMP command, specify DSPNAME= ('VLF'.Dclsname, 'VLF'.Cclsname), where clsname is a VLF class name. |
| SYSWLM | 64KB 64KB - 16M |
MVS system | Yes, when starting a trace | Extended common service area (ECSA) |
| SYSXCF | 4MB 16KB - 16MB (System rounds size up to a multiple of 72 bytes.) |
CTnXCFxx member | No | Extended local system queue area (ELSQA) of the XCF address space |
| SYSXES | 336KB 16KB - 16MB |
CTnXESxx member or REPLY for TRACE CT command | Yes, while a trace is running. | Data space. In the REPLY for the DUMP command, specify SDATA=XESDATA and DSPNAME= (asid.IXLCTCAD) where asid is the ASID for address space XCFAS |