Derivation: IO HEAP storage for AMODE 64

IOHEAP64 controls the allocation of I/O heap storage for AMODE 64 applications and specifies how that storage is managed. Language Environment uses this storage when performing I/O for AMODE 64 applications.

AMODE 64 default

IOHEAP64=((1M,1M,FREE,12K,8K,FREE,4K,4K,FREE),OVR)

Syntax

                                            .-KEEP-.      
>>-IOHEAP64--=--(--(--init64--,--incr64--,--+-FREE-+--,--------->

                         .-KEEP-.                            
>--init31--,--incr31--,--+-FREE-+--,--init24--,--incr24--,------>

   .-FREE-.        .-OVR----.      
>--+-KEEP-+--)--,--+-NONOVR-+--)-------------------------------><

init64

Determines the initial allocation of I/O heap storage obtained above the 2G bar. Specify this value as nM bytes of storage. If a value of 0 or less is specified, the default is used.

incr64

Determines the minimum size of any subsequent increment to the I/O heap storage obtained above the 2G bar. Specify this value as nM bytes of storage. If a value less than 0 is specified, the default is used.

KEEP

Specifies that an increment to I/O heap storage is not released when the last of the storage within that increment is freed.

FREE

Specifies that an increment to I/O heap storage is released when the last of the storage within that increment is freed.

init31

Determines the minimum initial size of I/O heap storage that is obtained above the 16MB line and below the 2GB bar. This value can be specified as n, nK, or nM number of bytes. If a value of 0 or less is specified, the default is used. The amount of allocated storage is rounded up to the nearest multiple of 8 bytes.

incr31

Determines the minimum size of any subsequent increment to I/O heap storage that is obtained above the 16MB line and below the 2GB bar. This value can be specified as n, nK, or nM number of bytes. If a value less than 0 is specified, the default is used. The amount of allocated storage is rounded up to the nearest multiple of 8 bytes.

init24

Determines the minimum initial size of I/O heap storage that is obtained below the 16MB line. This value can be specified as n, nK, or nM number of bytes. If a value of 0 or less is specified, the default is used. The amount of allocated storage is rounded up to the nearest multiple of 8 bytes.

incr24

Determines the minimum size of any subsequent increment to I/O heap storage that is obtained below the 16MB line. This value can be specified as n, nK, or nM number of bytes. If a value less than 0 is specified, the default is used. The amount of allocated storage is rounded up to the nearest multiple of 8 bytes.

OVR

Specifies that the option can be overridden.

NONOVR

Specifies that the option cannot be overridden.

Performance considerations

To improve performance, use the storage report numbers generated by the RPTSTG runtime option as an aid in setting the initial and increment sizes for IOHEAP64.

For more information

See RPTSTG for more information about the RPTSTG runtime option.