Function 4Ah (74)        Modify Memory Allocation (SETBLOCK)

Changes the size of a memory block that was allocated via Function
48h.

On entry:      AH         4Ah
BX         New block size, in paragraphs
ES         Segment address of the memory block to be
modified

Returns:       AX         Error code, if CF is set
BX         Maximum memory available, if CF is set and
request was to expand memory block

Error codes:   7          Memory control blocks destroyed
8          Insufficient memory
9          Invalid block address

Call Function 59h for extended error code information
(DOS 3.0 and above).

                                                                          

This function is used to increase or decrease the size of a memory
block allocated by Function 48h. ES contains the segment address of
the block whose size will be changed. BX contains the new size of the
block, in paragraphs (16-bytes units).

See also: 48h
See also: 49h
See also: 59h

4Ah (74) Modify Memory Allocation (SETBLOCK)