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.
The
default value for AMODE 64 applications is IOHEAP64(1M,1M,FREE,12K,8K,FREE,4K,4K,FREE).
Syntax
.-KEEP-. .-KEEP-.
>>-+-IOHEAP64-+--(--+--------+--,--+--------+--,--+------+--,--+--------+--,--+--------+--+------+-->
'-IH64-----' '-init64-' '-incr64-' '-FREE-' '-init31-' '-incr31-' '-FREE-'
.-KEEP-.
>--,--+--------+--,--+--------+--+------+--)-------------------><
'-init24-' '-incr24-' '-FREE-'
- 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 16M line and below the 2G bar. This value can be
specified as n, nK,
or nM number of bytes. If 0 is specified,
the initial storage is obtained on the first use and is based on the
increment size. 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 16M line and below the 2G
bar. This value can be specified as n, nK,
or nM number of bytes. 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 16M line. This value can be specified as n, nK,
or nM number of bytes. If 0 is specified,
the initial storage is obtained on the first use and is based on the
increment size. 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 16M line. This value can be
specified as n, nK,
or nM number of bytes. The amount of allocated
storage is rounded up to the nearest multiple of 8 bytes.
Performance consideration
You can improve
performance with the IOHEAP64 runtime option by
specifying values that minimize the number of times the operating
system allocates storage. See RPTSTG for
information about how to generate a report you can use to determine
the optimum values for the IOHEAP64 runtime option.