This call reallocates a segment after discard or changes the size of a segment already allocated.


DosReallocSeg (Size, Selector)


;Size (USHORT) - input : New requested segment size (in bytes). A value of 0 indicates 65536 bytes. ;Selector (SEL) - input : Segment to be resized.

Return Code

rc (USHORT) - return Return code descriptions are: * 0 NO_ERROR * 5 ERROR_ACCESS_DENIED * 8 ERROR_NOT_ENOUGH_MEMORY


DosReallocSeg is called to change the size of an unshared or shared segment allocated with a DosAllocSeg request.

Normally, segments allocated as shared (AllocFlags bits 0 and 1 were set) cannot be decreased in size. However, if AllocFlags bit 3 was also set, the shared segment's size can be decreased.

DosReallocSeg is also called to reallocate a segment allocated as discardable (AllocFlags bit 2 set) after the segment is discarded by the system. The call to DosReallocSeg automatically locks the segment for access by the caller, the same as if a DosLockSeg had been issued.

Note: This request may be issued from privilege level 2 or 3, and the segment being resized can be either a privilege level 2 or privilege level 3 segment.

To change the size of huge memory allocated by DosAllocHuge, see DosReallocHuge.

Family API Considerations

Some options operate differently in the DOS mode than in the OS/2 mode. Therefore, the following restriction applies to DosReallocSeg when coding for the DOS mode. The requested Size value is rounded up to the next paragraph (16-byte).

Example Code

C Binding


USHORT rc = DosReallocSeg(Size, Selector);

USHORT Size; /* New size requested in bytes */ SEL Selector; /* Selector */

USHORT rc; /* return code */ </PRE>

MASM Binding


PUSH WORD Size ;New size requested in bytes PUSH WORD Selector ;Selector CALL DosReallocSeg

Returns WORD </PRE>


en/docs/fapi/dosreallocseg.txt · Last modified: 2020/12/05 11:44 by prokushev