MPE/iX Intrinsics Reference Manual (32650-90875)

52 Chapter4
Command Definitions (ABORTSESS - FCLOSE)
ALTDSEG
ALTDSEG
NM and CM callable.
Reduces the storage required by the extra data segment when moved into main memory
and expands storage as required, allowing for a more efficient use of memory. Data
segment management (DS) capability is required.
NOTE Data segment management (DS) intrinsics are not recommended for use in
the operating system native mode programming environment; use of DS
intrinsics degrade program performance.
Syntax
U16V I16V I16
ALTDSEG(
index,increment,size );
Parameters
index 16-bit unsigned integer by value (required)
Indicates the index of the extra data segment, obtained from the GETDSEG
call.
increment 16-bit signed integer by value (required)
Specifies the value, in half words, the extra data segment is to be changed.
A positive value requests an increase; a negative value requests a
decrease.
size 16-bit signed integer by reference (required)
Returns the new size of the extra data segment after incrementing or
decrementing has occurred.
Operation Notes
Incrementation and decrementation is accomplished in even multiples of four half words,
which are rounded up. For example (in half words):
Present Segment Size Change Value New Segment Size
128 -3 128
128 -4 124
128 +1 132
128 +3 132
128 +4 132