Milestone 12: Enabling high-performance breakpointing
Code Debug TSO and Code Debug IMS can be configured to utilize a high-performance breakpoint processing methodology. This improved breakpoint system uses a TYPE 6 Supervisor Call (SVC) that significantly reduces the overhead of breakpoint processing. If using the TRAP instruction, the overhead is reduced even more. The result is faster response and run times with less system overhead than traditional breakpoint processing. SVC breakpoint processing is optional, however, and does not need to be installed for Code Debug to function properly.
If your site is not using—and does not plan to use—high-performance breakpointing, go to Milestone 13: Deployment.
Roles Involved
The following people are required for this milestone:
Tasks
Complete the following tasks to implement high-performance breakpointing.
Task 12.1 Gather Configuration Information
The following person is required for this task:
To implement SVC breakpointing, two items of information are required:
- The name of an MVS APF authorized library
- An SVC number between 200 and 255 inclusive.
If necessary, consult your site’s z/OS System Programmer to obtain this information.
Task 12.2 Define SVC Number
The following person is required for this task:
Code Debug TSO and Code Debug IMS need to be informed of the SVC number. This is done by customizing the options CTLUSVC, CTLSVCNO, and CTLUTRAP. These options can be overridden in the CMSC PARMLIB member. See CTLUTRAP, CTLUSVC, and CTLSVCNO in the section entitled Run-Time Parameter Keywords in the Code Debug TSO and Code Debug IMS Advanced Configuration Space for more information about specifying the method of breakpoint processing.
Task 12.3 Install High Performance Breakpoint SVC Code
The following person is required for this task:
The SVC number that you have been given needs to be defined to the MVS operating system. This is done by running the SVC Installation Utility program. Sample JCL for executing the utility program is provided in the SLXTINST library, member JCLSVCIN.
- Use the XTUPDATE macro to configure SLXTINST(JCLSVCIN).
- The PARM values are:
PARM='OPTION=INSTALL,SVC=sss,WAIT=Y'where sss is the SVC number supplied to you by the z/OS Systems Programmer. - Submit the JCL. It should end with return code 0.
Task 12.4 Configure z/OS to Start the SVC Call After an IPL
The following person is required for this task:
JCLSVCIN must be run after each IPL to re-enable the high-performance breakpointing. If you want JCLSVCIN to run automatically during z/OS startup, perform the following:
- Copy SLXTINST(JCLSVCIN) to one of your installation PROCLIBs and use XTUPDATE to customize the JCL to run as a batch job.
- Modify JCLSVCIN to meet your site’s standards for a z/OS startup procedure, replacing the JOB statement with a PROC statement.
- Verify that the PARM statement’s OPTION parameter is set to INSTALL, the SVC parameter is set to the correct SVC number, and the WAIT parameter is set to Y (Yes).
- Configure your z/OS system to start JCLSVCIN at IPL time by either:
- Updating your z/OS PARMLIB member COMMNDxx.
- Configuring your automated operations application.
An example of the START command is provided in SLXTINST(COMMNDxx).