Symbols

When an IPCS subcommand accepts a literal value, the value can be entered as a symbol. The definition of the symbol and the data associated with the symbol are contained in the dump directory. You can use symbolic literals so that IPCS can manage many dumps and traces without having to allocate and open the dump and trace data sets frequently.

Defining a Symbol
Define a symbol using a LITERAL subcommand. For example:
```
literal a c'ABCDE'
```
If the EVALUATE subcommand requests a storage key for a symbolic literal, IPCS returns the FF value used when the storage key is not available.

Note: IBM® does not recommend using a symbolic literal as the basis for indirect addressing. IPCS will accept such an indirect address and try to resolve it to the appropriate dumped central storage, but may not be able to resolve it depending on the dump and the local and global defaults in effect.
If you define a symbol based on a literal symbol, the resulting definition is an independent copy of the literal data. For instance:
```
literal a c'X'
equate b a
literal a c'Y'
```
This sequence leaves symbol A associated with C'Y' and symbol B associated with C'X', rather than C'Y'. This sequence is consistent with the following EQUATE subcommands, which leave symbol F with the same definition as symbol ASVT and symbol G with the same definition as symbol CVT.
```
equate f cvt
equate g f
equate f asvt
```
Referring to a Symbolic Literal
An IPCS command or subcommand refers to the name of the address space containing the literal as LITERAL and refers to the literal by its symbol. For example:
```
literal(a)
```
Location of a Symbol
IPCS treats each literal value as residing in the first 1 through 256 bytes of an address space that it shares with no other literals. Because an address space contains 2³¹ bytes, most or all bytes in the address space for a symbolic literal are not available. The following sequence of subcommands associates symbol Y with an address space in which no bytes are available:
```
literal x c'Q'
equate y x position(10) length(10) character
```
Only the first byte of the address space was populated by the LITERAL subcommand. The EQUATE subcommand tries to define symbol Y with 10 bytes of storage that are not available.