TRAPON subcommand — activate IPCS traps

Use the TRAPON subcommand to activate IPCS-supplied traps. If you write your own installation exit and use one of the exit service routines, which are described in z/OS MVS IPCS Customization, use the TRAPON, TRAPOFF, and TRAPLIST subcommands to obtain diagnostic input and output information. You can also use these subcommands to set traps when executing IPCS code that uses the exit service routines.

If a TRAPON subcommand requests several traps, IPCS activates only supported traps. Whenever an unsupported trap is requested, IPCS issues the following message:

BLS17014I Trap of INPUT/OUTPUT(trap) is not supported for service(sss)

where sss is the name of the requested exit service routine.

Note: Activated traps are not retained between IPCS sessions.

During STOP processing, all traps are temporarily deactivated until the GO subcommand is entered to resume the stopped operation. This temporary deactivation of traps is done because some of the subcommands available during STOP processing also use exit services and therefore are also trapped.

Related subcommands
- TRAPOFF
- TRAPLIST
- GO

Syntax

    TRAPON    { ALL         }
              { code        }
              { (code-list) }
              [INPUT   [([ABDPL] )  ]]
              [        [ [DATA]     ]]
              [        [ [PARMS]    ]]
              [        [ [STOP]     ]]
              [                      ]
              [NOINPUT               ]
              [OUTPUT   [([RETC] )  ]]
              [         [ [DATA]    ]]
              [         [ [PARMS]   ]]
              [         [ [STOP]    ]]
              [         [ [ERROR]   ]]
              [                      ]
              [NOOUTPUT              ]

Parameters
ALL

code

code-list

Identifies the IPCS-supplied traps to be activated. ALL specifies all IPCS-supplied traps. All is the default; if you do not specify any codes, IPCS activates all traps.
code specifies a code that identifies an IPCS-supplied exit service routine.

code-list specifies a list of codes. When you specify a list, separate the list members with commas and enclose the list in parentheses. Otherwise, parentheses are optional.

The codes are:
Code

Exit Service Routines

ACC

Storage access service

ADS

Add symptom service

CBF

Control block formatter service

CBS

Control block status service

CQE

Contention queue element create service

CSI

CSVINFO macro

ECT

ECT exit service

EQS

Equate symbol service

FMT

Format model processor service

GTS

Get symbol service

MAP

Map service

NAM

Name service

NDX

Table of contents service

NTK

NAME/TOKEN lookup service

PRT

Standard print service

PR2

Expanded print service

SEL

Select ASID service

SYM

Symbol service

WHS

WHERE service

INPUT
Specifies that trap processing is to be done before performing a requested service. If the INPUT parameter is specified without any options, all supported input trapping options are activated. The options are:
Option

Processing

ABDPL

Displays the common exit parameter list and its extension that are passed to all services.

DATA

Displays data passed to a service in addition to basic parameters. The DATA option can be used only if the FMT code is specified.

PARMS

Displays parameters passed to a service. The PARMS option cannot be used if the PRT and NDX codes are specified.

STOP
Halts IPCS processing and prompts you for input before performing a service. If the TSO/E NOPROMPT mode is in effect when STOP processing is attempted, processing is not interrupted. During STOP processing, only the following may be entered:
IPCS subcommands GO, HELP, NOTE, TRAPLIST, TRAPOFF, TRAPON, and TSO. Use the GO subcommand to resume processing; the END subcommand is not valid.

CLISTs and REXX execs that contain only the previously mentioned subcommands.

TSO/E commands that are normally accepted during an IPCS session. The use of authorized TSO/E commands requires the installation of TSO/E Release 2 or a later release.

Restriction: If you specify INPUT(STOP) or OUTPUT(STOP) when running IPCS in the background or in a full-screen dialog, it is ignored.
See Example 1 for a list of the trap options supported by the INPUT and OUTPUT parameters for each exit service routine.
NOINPUT

Specifies that no trap processing is to be done before performing a requested service. NOINPUT is the default.
Note: If both NOINPUT and NOOUTPUT are specified, IPCS issues a diagnostic message, and the TRAPON subcommand ends without alteration to the status of the traps.

OUTPUT
Specifies that trap processing is to be done before returning to the caller of a service. If the OUTPUT parameter is specified without any options, all supported output trapping options are activated. The options are:
Option

Processing

RETC

Displays the return code from the service and the service code-list.

DATA

Displays the data returned by a service in addition to basic parameters. The DATA option can be used only if the ACC and SEL codes are specified.

PARMS

Displays parameters returned by a service. This is the same parameter list that is displayed as input, but it will show any values changed by the service. The PARMS option cannot be used if the PRT and NDX codes are specified.

STOP
Halts IPCS processing and prompts you for input before returning from a service. If the TSO/E NOPROMPT mode is in effect when STOP processing is attempted, processing is not interrupted, and no message is issued. During STOP processing only the following may be entered:
IPCS subcommands GO, HELP, NOTE, TRAPLIST, TRAPOFF, TRAPON, and TSO. Use the GO subcommand to resume processing; the END subcommand is not valid.

CLISTs and REXX execs that contain only the previously mentioned subcommands.

TSO/E commands that are normally accepted during an IPCS session. The use of authorized TSO/E commands requires the installation of TSO/E Release 2 or a later release.

Restriction: If you specify OUTPUT(STOP) or INPUT(STOP) when running IPCS in the background or in a full-screen dialog, it is ignored.
ERROR

Specifies that the other output trap actions are to take place only when the return code from the service is not zero. This is a convenient means of reducing the output from the trap facility, but still seeing important failure-related information.
See Example 1 for a list of the trap options supported by the INPUT and OUTPUT parameters for each exit service routine.
NOOUTPUT

Specifies that no trap processing is to be done before returning to the caller of a service. NOOUTPUT is the default.
Note: If both NOINPUT and NOOUTPUT are specified, IPCS issues a diagnostic message, and the TRAPON subcommand ends without alteration to the status of the traps.
Return Codes
See Standard subcommand return codes for a description of the return codes produced by the TRAPON subcommand.
Example 1: Turn on all traps associated with the exit service routines.
- Action
```
COMMAND ===> trapon all input(abdpl,parms)
```
- Result
  This example activates the trap for all the exit services. When a trap is hit, the ABDPL and the parameter list (if used) are displayed.
Example 2: Turn on all traps and all options associated with the storage access and the control block formatter service routines and display the return code on exit.
- Action
```
COMMAND ===> trapon (acc cbf) output(retc)
```
- Result
  This example activates the traps for the storage access and the control block formatter service routines and displays the return code on exit from these services.