Purpose and Use of Symbol Tables and Symbols

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# Purpose and Use of Symbol Tables and Symbols

This document covers the following topics:

- Symbol Tables

- Symbols

- Handling Active Symbol Tables and Active Symbols

- Subnetworks and Recovery Jobs

- User Exits for User-Specific Symbol Maintenance Tasks

#### Related Topic:

- Symbol Tables and Symbols in the Concepts and Facilities documentation

## Symbol Tables

A symbol table is used to maintain common parameter definitions that apply to all jobs of a network. A symbol table contains a list of defined symbols with values that can be used for parameter substitution during JCL generation.

You can substitute symbols when activating a job network or a job, that is, when the active JCL is loaded to the active database. You can also substitute symbols when submitting a job.

Each network activation initiates its own active copy (active symbol table) of the linked symbol table(s). This allows you to schedule networks with different parameter sets, even a long time in advance. Any occurrence of a symbol name in the JCL or in a script is replaced by its current value.

You can maintain symbol tables by using either Entire Operations maintenance functions or user-written programs, user exits and application programming interfaces (APIs) supplied by Entire Operations. This allows modification of symbol tables and symbol values during job network processing.

Symbol tables are associated with owners. Each owner can have several symbol tables. You can only maintain the symbol tables that belong to your owner.

The symbol table to be referenced by a job and/or network must be specified in the job or network master definition or in the active queue for a single job run. Exceptions are global symbol tables.

This section covers the following topics:

- Global Symbol Tables

- Active Symbol Tables

- Reserved Symbol Table Name

- Symbol Table Versions and Version Usage

### Global Symbol Tables

A symbol table master defined by the owner SYSDBA is considered a global symbol table because it can be references by multiple jobs and networks without explicit specifications in the job and network definitions. A global symbol table with the name `A` is supplied for the owner SYSDBA by default. It can be accessed and referenced by all owners.

All other owners can also define a global symbol table with the name `A` for their networks. Their global symbol table `A` then takes priority over the global symbol table `A` defined by SYSDBA. See also Symbol Table Types and Symbol Search Order.

### Active Symbol Tables

During job or network activation, an active copy of each symbol table used by a job or network is created by copying it to the active database. This is then called the active symbol table. Symbols to be replaced are taken from the active symbol table. This enables different values of the same symbols to be generated for different runs of the network or job.

See also Handling Active Symbol Tables and Active Symbols.

### Reserved Symbol Table Name

The symbol table name with the prefix `=EOR=` is reserved for internal control purposes. This prefix must not be used for any user-defined table names.

### Symbol Table Versions and Version Usage

You can maintain several versions of a symbol table master as described in Versioning of Symbol Tables. Exceptions are global symbol tables for which versioning is not allowed.

If you have several symbol table versions, you can define a validity period for each version. See the section Maintaining the Usage of Symbol Table Versions.

## Symbols

A symbol is a variable definition that contains the format, prompting type, prompting text (optional) and the value(s) of the symbol.

Symbols can be defined by using Entire Operations maintenance functions, or they can be set and modified by any program, which invokes the Entire Operations symbol API NOPUSY7N (see the section API Routines) to set, reset, or modify a symbol.

For detailed information on defining symbols in JCL (including text objects) or Natural macro sources, see Editing Master JCL and Natural Sources and Inserting Text Objects into the JCL in the section Job Maintenance.

This section covers the following topics:

- Global Symbols

- Predefined Symbols

- Symbols for Replacement

- Symbol Prompting

### Global Symbols

A symbol master contained in a global symbol table is considered a global symbol because it can be used by multiple jobs and networks without extra definitions for each job and/or network that references the symbol. See also Global Symbol Tables.

### Predefined Symbols

Predefined symbols provided by Entire Operations are described in the section Predefined Symbols.

### Symbols for Replacement

Symbols are usually replaced during the activation of a job network or job, that is, during the loading of the active JCL to the active database. In certain cases, symbol replacement can even be used in file names, messages texts, etc.

A symbol to be replaced is identified by an escape character defined in the Entire Operations default and network settings, or used as a prefix in JCL and Natural macro sources. You specify the symbols in JCL or macro sources as described in Defining Escape Characters.

If a symbol is not found in the symbol table specified for a job or network, the symbol is searched for in the global symbol table(s). The first match is used to replace the symbol. A symbol is not replaced if it cannot be found in any table; an appropriate error message is then issued instead. See also Symbol Table Types and Symbol Search Order.

For further information, see the section Symbol Replacement.

### Symbol Prompting

You can define whether a symbol is prompted for symbol modification during or before job network activation.

- During a manual network or job activation, the prompting is performed immediately. See the section Symbol Prompting during Network or Job Activation.

- For scheduled (automatic) activations, prompting requests are sent to a mailbox linked to the network. The network activation does not continue until the prompting is performed by a user. See also Specifying Recipients for Network Messages in the section Network Maintenance.

## Handling Active Symbol Tables and Active Symbols

Active symbol tables are used to provide symbols for a selected job run. You can add, modify or delete the symbol of an active symbol table without affecting the symbol definitions in the symbol table master.

By default, modifications to an active symbol apply to the current run only. However, if the Update Mode option (see Fields: Symbol) is activated in a symbol master or active symbol definition window, modifications or additions apply to both the active symbol of the current run and the symbol master.

A symbol table is usually activated when a network or job is activated (see also Activation of Networks or Jobs), or when symbol prompting is performed.

For scheduled network activation, you can determine the time to activate the symbol tables defined in the network and job definitions. This can be either of the following:

- Directly after schedule extraction; this allows enough time for manual symbol replacement.

- During network activation. In this case, however, manual symbol replacement is not possible.

Active symbol tables are accessed through the Active Job or All Active Jobs list screen opened by the Active Job Networks or Network Maintenance function if job runs are available for a requested network.

This section covers the following topics:

- Performing Maintenance Functions

### Performing Maintenance Functions

You can only modify, add/copy or delete symbols if you are granted permission in your user profile or if the containing symbol table belongs to an owner to whom you are linked and who has permission to perform these operations. See also your Symbol Tables profile setting for Network Maintenance Functions described in the Administration documentation.

Active symbols are maintained analogously to symbol masters. In general, all maintenance functions, fields and columns provided for symbol masters are also provided for active symbols. Functional differences are documented where relevant.

## Subnetworks and Recovery Jobs

Subnetworks and recovery jobs defined for a network require predefined symbols to pass information to the jobs of the network. These predefined symbols have names that begin with `P-C-`. For detailed information, see Predefined Symbols for Subnetworks and Recovery Jobs.

## User Exits for User-Specific Symbol Maintenance Tasks

You can use user exit routines that perform user-specific symbol maintenance tasks and symbol replacement functions. For detailed information, refer to the following sections:

> User Exits:

>   - User Exits for Validation Checks of Symbol Values

>   - User Exits for Symbol Functions

> Global User Exits in the Administration documentation:

>   - Global Symbol Modification Exit

>   - Global Symbol Not Found Exit

### On this page

- Symbol Tables
- Symbols
- Handling Active Symbol Tables and Active Symbols
- Subnetworks and Recovery Jobs
- User Exits for User-Specific Symbol Maintenance Tasks