PL/I Dictionary

A data attribute that specifies that the data item may be changed unexpectedly, such as by occurrence of an ON condition. ABNORMAL is the opposite of NORMAL.

An ADJUSTABLE data element is a string, array, or area whose [maximum] string length and/or array extents, or area size is determined at run time when the data item is allocated. Once the item is allocated the extent, length or size is fixed for that generation of the data. Structures containing adjustable data are adjustable structures.

A storage class which defines the attributes but not the location of a data item. The address of the data must be provided when it is referenced.

A storage class where the data must be explicitly allocated and freed by the program. Storage is maintained as a push-down list where only the most recently allocated generation is normally accessable at any time.

A PL/I preprocessor (macro) statement which instructs the compiler to insert program text from a named external file.

A data attribute specifing the value or values assigned to a data item at the time storage is allocated for it.

IRREDUCIBLE

An entry attribute telling the compiler that multiple calls to this entry with the same parameters cannot be reduced to a single call. That is, the entry does not necessarily return identical values for calls with the same set of parameters or has side effects. IRREDUCIBLE is the opposite of REDUCIBLE.

A data attribute that specifies that the data item will not be changed unexpectedly, such as by occurrence of an ON condition. NORMAL is the opposite of ABNORMAL.

ON-condition

An occurrence within a PL/I program of a condition that could cause a program interrupt, such as division by zero.

A data attribute which uses a mask, called a picture specification, to define the expected contents of a character string in terms of both data and editing characters. For example the declaration
DECLARE A PICTURE '$$$$,$$$.99-';
declares A as a 12-character item consisting of 8 decimal digits, a "floating" currency-symbol, a trailing sign, and the editing characters comma and decimal-point. Data will be edited and de-edited automatically when moved from and to the field.

An attribute declaring an identifier which "points to" a location in storage. A pointer is usually, but not necessarily, synonymous with a hardware "storage address."

PSEUDOVARIABLE

A builtin function used to specify a target variable, for example used on the left hand side of an assignment. Only certain builtins may be used as pseudovariables. SUBSTR is used as a pseudovariable in the statement:

     SUBSTR(a,1,2)='  ';

An entry attribute telling the compiler that multiple calls to this entry with the same parameters can be reduced to a single call. That is, the entry returns identical values for calls with the same set of parameters and has no side effects. REDUCIBLE is the opposite of IRREDUCIBLE.

An entry attribute providing a list of parameters which are modified by a call to this entry, to aid in optimization. (see USES.)

A PL/I statement which causes a specified ON-condition to be raised programatically.

An entry attribute providing a list of parameters which are referenced but not not modified by a call to this entry, to aid in optimization. (see SETS.)

A string attribute declaring that the string may contain between zero and a declared maximum number of characters or bits. The compiled code maintains the count of the "current" string length. VARYING strings may or may not be ADJUSTABLE.

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Last modified 26 May, 2013.