ISPF Services for REXX: Panel, Edit & Library Services

ISPF services provide REXX scripts with access to ISPF capabilities, enabling powerful automation and application development. REXX can use panel services to display interactive dialogs, edit services to work with datasets, and library services to manage ISPF libraries. Understanding ISPF services helps you create sophisticated REXX applications that integrate with ISPF. This tutorial covers panel services, edit services, library services, and how to use them in REXX scripts.

ISPF services extend REXX capabilities by providing access to ISPF functions. Panel services enable interactive user interfaces, edit services provide dataset operations, and library services manage ISPF library contents. Learning to use these services enables you to build powerful ISPF applications with REXX. This tutorial provides practical guidance for using ISPF services in REXX.

Understanding ISPF Services

ISPF services are functions that REXX can call to interact with ISPF.

What are ISPF Services?

ISPF services are:

• Functions accessible from REXX
• Provide ISPF capabilities to REXX scripts
• Called using ADDRESS ISPEXEC
• Return codes indicate success or failure
• Enable REXX-ISPF integration

ADDRESS ISPEXEC

The ADDRESS ISPEXEC command:

• Directs commands to ISPF
• Required for ISPF service calls
• Sets up ISPF environment
• Enables service access

Example:

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/*REXX*/
address ispexec
'DISPLAY PANEL(MYPANEL)'
if rc <> 0 then exit 8
exit 0

Panel Services

Panel services enable REXX to display and process ISPF panels.

DISPLAY PANEL

The DISPLAY PANEL service:

• Displays an ISPF panel
• Collects user input
• Returns when user exits panel
• Return code indicates how user exited

Example:

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/*REXX*/
address ispexec
'DISPLAY PANEL(MYINPUT)'
if rc = 0 then do
  say 'User entered:' zuser
end
else do
  say 'User cancelled'
  exit 8
end
exit 0

TBDISPL

The TBDISPL service:

• Displays table display panels
• Shows tabular data
• Allows row selection
• Returns selected row information

Panel Variables

Panel services use ISPF variables:

• Z variables for system information
• User-defined variables for input/output
• Variables accessible in REXX
• Set and retrieved through services

Edit Services

Edit services enable REXX to work with datasets.

EDIT DATASET

The EDIT DATASET service:

• Opens dataset in ISPF editor
• Allows programmatic edit operations
• Returns when editor closes
• Can specify member for PDS

Example:

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/*REXX*/
parse arg dsn member
address ispexec
if member <> '' then
  'EDIT DATASET('"'"dsn"("member")"'"')'
else
  'EDIT DATASET('"'"dsn"'"')'
if rc <> 0 then do
  say 'Error opening dataset'
  exit 8
end
exit 0

BROWSE DATASET

The BROWSE DATASET service:

• Opens dataset in ISPF browser
• Read-only viewing
• Useful for displaying data
• Can specify member for PDS

Example:

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/*REXX*/
parse arg dsn
address ispexec
'BROWSE DATASET('"'"dsn"'"')'
exit 0

VIEW DATASET

The VIEW DATASET service:

• Opens dataset in view mode
• Similar to browse
• Read-only access
• Alternative to browse

Library Services

Library services enable REXX to manage ISPF libraries.

LMINIT

The LMINIT service:

• Initializes library access
• Sets up library connection
• Returns dataset ID
• Required before other library operations

Example:

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/*REXX*/
parse arg libname
address ispexec
'LMINIT DATASETID(id) DATASET('"'"libname"'"')'
if rc <> 0 then do
  say 'Error initializing library'
  exit 8
end
/* Use library */
'LMFREE DATASETID(id)'
exit 0

LMOPEN

The LMOPEN service:

• Opens library for access
• After LMINIT
• Prepares library for operations
• Required for member access

LMMLIST

The LMMLIST service:

• Lists library members
• Returns member information
• Useful for member enumeration
• Can filter members

LMCLOSE and LMFREE

Library cleanup services:

• LMCLOSE closes library
• LMFREE frees library resources
• Should be called when done
• Prevents resource leaks

Table Services

Table services enable REXX to work with ISPF tables.

TBOPEN

The TBOPEN service:

• Opens ISPF table
• Prepares table for access
• Returns table handle
• Required for table operations

TBADD

The TBADD service:

• Adds row to table
• Inserts data into table
• Requires table to be open
• Returns success status

TBSAVE

The TBSAVE service:

• Saves table changes
• Persists table data
• Required to keep modifications
• Returns success status

TBCLOSE

The TBCLOSE service:

• Closes ISPF table
• Releases table resources
• Should be called when done
• Prevents resource leaks

Variable Services

Variable services enable REXX to handle ISPF variables.

VGET

The VGET service:

• Gets ISPF variable values
• Retrieves variable to REXX
• Can get single or multiple variables
• Makes variables available in REXX

Example:

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/*REXX*/
address ispexec
'VGET (ZUSER ZPREFIX)'
say 'User:' zuser
say 'Prefix:' zprefix
exit 0

VPUT

The VPUT service:

• Sets ISPF variable values
• Updates variables from REXX
• Can set single or multiple variables
• Makes REXX values available to ISPF

Example:

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/*REXX*/
address ispexec
mydsn = 'USERID.SOURCE.COBOL'
'VPUT (MYDSN)'
exit 0

Error Handling

Proper error handling is essential when using ISPF services.

Checking Return Codes

Always check return codes:

• RC = 0 indicates success
• RC > 0 indicates error or special condition
• Check RC after each service call
• Handle errors appropriately

Common Return Codes

Common return codes:

• 0: Success
• 4: Warning or user action (like cancel)
• 8: Error
• 12: Severe error

Error Handling Pattern

Standard error handling:

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/*REXX*/
address ispexec
'DISPLAY PANEL(MYPANEL)'
if rc <> 0 then do
  if rc = 4 then
    say 'User cancelled'
  else
    say 'Error displaying panel, RC=' rc
  exit rc
end
exit 0

Best Practices

Following best practices improves REXX-ISPF integration:

• Use ADDRESS ISPEXEC: Always use ADDRESS ISPEXEC for ISPF services
• Check Return Codes: Always check RC after service calls
• Handle Errors: Provide meaningful error handling
• Free Resources: Always free resources (LMFREE, TBCLOSE, etc.)
• Validate Input: Validate input before using services
• Use Appropriate Services: Choose the right service for the task
• Test Incrementally: Test services one at a time
• Document Service Usage: Document which services are used

Explain Like I'm 5: ISPF Services for REXX

Think of ISPF services like special tools REXX can use:

• ISPF Services are like special tools that REXX can borrow from ISPF. Just like you can borrow tools from a toolbox, REXX can use ISPF's tools (services) to do things like show screens, edit files, and manage libraries. It's like REXX asking ISPF "can I use your tools?" and ISPF saying "yes, here they are!"
• Panel Services are like tools for showing pictures and asking questions. REXX uses these tools to display screens (panels) to users and get their answers. It's like REXX using ISPF's tool to show a form and collect information!
• Edit Services are like tools for working with files. REXX uses these tools to open files for editing or viewing. It's like REXX using ISPF's tool to open a notebook and let you write in it or read it!
• Library Services are like tools for managing collections of things. REXX uses these tools to work with libraries (collections of panels, messages, etc.). It's like REXX using ISPF's tool to organize and find things in a filing cabinet!
• ADDRESS ISPEXEC is like telling REXX "when I say 'use this tool', I mean use ISPF's tool." It's like saying "hey REXX, when I ask for a tool, get it from ISPF's toolbox!"

So ISPF services are like special tools that REXX can borrow from ISPF to do things like show screens, edit files, and manage libraries!

Practice Exercises

Complete these exercises to reinforce your ISPF services skills:

Exercise 1: Use Panel Service

Practice panel: write REXX script that displays a panel, use DISPLAY PANEL, handle user input, check return codes, and learn panel services. Master panel services.

Exercise 2: Use Edit Service

Practice edit: write REXX script that opens dataset for editing, use EDIT DATASET, handle errors, verify operation, and learn edit services. Master edit services.

Exercise 3: Use Library Service

Practice library: write REXX script that accesses ISPF library, use LMINIT and LMOPEN, list members, free resources, and learn library services. Master library services.

Exercise 4: Use Variable Service

Practice variable: write REXX script that gets and sets ISPF variables, use VGET and VPUT, understand variable handling, and learn variable services. Master variable services.

Exercise 5: Complete Application

Practice complete: write REXX script using multiple ISPF services, create interactive application, handle errors properly, and learn service integration. Master ISPF services integration.

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