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
- 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.
- 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.