DYNALLOC — Dynamic allocation

Description

Use the DYNALLOC macro to invoke dynamic allocation functions. Before attempting to use this macro, you must read the chapters “Dynamic Allocation” and “Requesting Dynamic Allocation Functions” in z/OS MVS Programming: Authorized Assembler Services Guide, for complete information on DYNALLOC.

Environment

Requirements for the caller are:

Environmental factor	Requirement
Minimum authorization:	Problem state or supervisor state, and any PSW key
Dispatchable unit mode:	Task
Cross memory mode:	PASN=HASN=SASN
AMODE:	24- or 31- or 64-bit
ASC mode:	Primary
Interrupt status:	Enabled for I/O and external interrupts
Locks:	No requirement
Control parameters:	Must be in the primary address space

Programming requirements

The calling program must include the following mapping macros to construct the SVC 99 parameter list:

IEFZB4D0
IEFZB4D2

See z/OS MVS Programming: Authorized Assembler Services Guide for details on constructing the parameter list.

Restrictions

See z/OS MVS Programming: Authorized Assembler Services Guide for programming restrictions and limitations.

Register information

On entry to the macro, general purpose register 1 must contain the address of a pointer to the SVC 99 parameter list structure. See z/OS MVS Programming: Authorized Assembler Services Guide for a detailed description of the parameter list.

After the caller issues the macro, the system might use some registers as work registers or might change the contents of some registers. When the system returns control to the caller, the contents of these registers are not the same as they were before the caller issued the macro. Therefore, if the caller depends on these registers containing the same value before and after issuing the macro, the caller must save these registers before issuing the macro and restore them after the system returns control.

When control is returned to the calling program the GPRs contain:

Register: Contents
0-1: Used as work registers by the system
2-14: Unchanged
15: Return code

Performance implications

There are no performance implications when the restrictions and limitations are all met.

Syntax

The DYNALLOC macro is written as follows:

Syntax	Description

`name`	`name`: Symbol. Begin `name` in column 1.

␢	One or more blanks must precede DYNALLOC

DYNALLOC

␢	One or more blanks must follow DYNALLOC

Parameters

There are no parameters for DYNALLOC.

Return and reason codes

When control returns from DYNALLOC, GPR 15 contains a return code. The return codes and associated reason codes are described in z/OS MVS Programming: Authorized Assembler Services Guide.