How Program Access (PA) keys affect ISPF operation

The two Program Access (PA) keys are defined as follows. These definitions cannot be changed.

ATTENTION (PA1): Normally, you should not use this key while you are in ISPF full-screen mode. The text following discusses exceptions.
RESHOW (PA2): Redisplays the contents of the screen. PA2 can be useful if you have pressed the ERASE INPUT or CLEAR key accidentally or have typed unwanted information but not yet pressed the Enter key or a function key.

Generally, PA1 is used to terminate TSO commands or CLISTs running under ISPF. However, some TSO commands and CLISTs process PA1 in their own way.

Note:

If you are running in GUI mode, you must switch back to your host session to process PA1.
If you are running in GUI mode, you must press Alt-Home (that is, hold down the Alt key and press the Home key) to process PA2 from the GUI display.

Restrictions that apply to CLIST attention exits are described in the z/OS ISPF Dialog Developer's Guide and Reference. Also, ISPF should not be started from a CLIST that contains an attention exit because results are unpredictable.

If PA1 is pressed while ISPF is in full-screen mode after the keyboard has been unlocked, it is treated as a RESHOW request. If PA1 is pressed again, the current function is terminated and either the primary option menu or a top-level selection panel supplied by the dialog developer is displayed.

When an ISPF function is running, if the RESET key is pressed to unlock the keyboard and PA1 is pressed, ISPF attempts to terminate the current function and redisplay the primary option menu. The attempt might not always be successful; for example, if there is an error in MVS™ allocation, the attempt fails. A failure might cause unpredictable results such as waits, loops, abends, or incorrect and unrelated error messages.