Requesting an attention interrupt during interactive sessions

During an interactive z/OS® Debugger session, you can request an attention interrupt, if necessary. For example, you can stop what appears to be an unending loop, stop the display of voluminous output at your terminal, or stop the execution of the STEP command.

An attention interrupt should not be confused with the ATTENTION condition. If you set an AT OCCURRENCE or ON ATTENTION, the commands associated with that breakpoint are not run at an attention interrupt.

Language Environment TRAP and INTERRUPT run-time options should both be set to ON in order for attention interrupts that are recognized by the host operating system to be also recognized by Language Environment. The test_level suboption of the TEST run-time option should not be set to NONE.

An attention interrupt key is not supported in the following environment and debugging modes:

  • CICS®
  • full-screen mode using the Terminal Interface Manager

For MVS only: For C, when using an attention interrupt, use SET INTERCEPT ON FILE stdout to intercept messages to the terminal. This is required because messages do not go to the terminal after an attention interrupt.

For the Dynamic Debug facility only: The Dynamic Debug facility supports attention interrupts only for programs that have compiled-in hooks.

The correct key might not be marked ATTN on every keyboard. Often the following keys are used:
  • Under TSO: PA1 key
  • Under IMS: PA1 key
When you request an attention interrupt, control is given to z/OS Debugger:
  • At the next hook if z/OS Debugger has previously gained control or if you specified either TEST(ERROR) or TEST(ALL) or have specifically set breakpoints
  • At a __ctest() or CEETEST call
  • When an HLL condition is raised in the program, such as SIGINT in C

Refer to the following topics for more information related to the material discussed in this topic.

  • Related references
  • z/OS Language Environment Programming Guide