PL/I considerations for using the CICS HANDLE ABEND command

The EXEC CICS® HANDLE facility resembles a PL/I ON-unit with this syntax:

ON condition GO TO label;

You can code the HANDLE command wherever you would code the ON...GO TO...statement. The label to be branched to can be located in any other active block, and the condition can arise in an even later block. HANDLE terminates intervening PL/I blocks by invoking PL/I's out-of-block GO TO facilities.

Note: Because PL/I internal procedures are not active at all times, you should not use internal procedures as exit routines in HANDLE commands.

HANDLE is not semantically identical to the ON condition GO TO label; statement. A PL/I ON-unit disappears when the block containing it terminates; a CICS HANDLE disappears permanently when it is explicitly overridden by another one at the same logical LINK level.

A HANDLE command could specify a branch to a label in a block no longer active. Because HANDLE is implemented by forcing a PL/I out-of-block GO TO, this is equivalent to assigning a label constant to a PL/I label variable after the block containing the label constant has terminated, which is invalid. The PL/I out-of-block GO TO mechanism attempts to detect this error and raises the ERROR condition. If PL/I out-of-block GO TO fails to detect such an invalid GO TO, however, the GO TO becomes a wild branch that causes some unpredictable failure. Thus, upon return from a PL/I block that established HANDLE for a particular condition, your program should issue a resetting HANDLE for that condition (provided, of course, that there is still some possibility of the condition arising). A PL/I ON-unit does not have to be reset.