Specifies the segment where uninitialized variables are stored in the .obj file.

#pragma bss_seg( [ [ { push | pop }, ] [ identifier, ] ] [ "segment-name" [, "segment-class" ] )


Obj files can be viewed with the dumpbin application. The default segment in the .obj file for uninitialized data is .bss. In some cases use of bss_seg can speed load times by grouping uninitialized data into one section.

bss_seg with no parameters resets the segment to .bss.

  • push(optional)
    Puts a record on the internal compiler stack. A push can have an identifier and segment-name.

  • pop (optional)
    Removes a record from the top of the internal compiler stack.

  • identifier (optional)
    When used with push, assigns a name to the record on the internal compiler stack. When used with pop, pops records off the internal stack until identifier is removed; if identifier is not found on the internal stack, nothing is popped.

    identifier enables multiple records to be popped with a single pop command.

  • "segment-name"(optional)
    The name of a segment. When used with pop, the stack is popped and segment-name becomes the active segment name.

  • "segment-class" (optional)
    Included for compatibility with C++ prior to version 2.0. It is ignored.


// pragma_directive_bss_seg.cpp
int i;                     // stored in .bss
#pragma bss_seg(".my_data1")
int j;                     // stored in "my_data1"

#pragma bss_seg(push, stack1, ".my_data2")   
int l;                     // stored in "my_data2"

#pragma bss_seg(pop, stack1)   // pop stack1 from stack
int m;                     // stored in "stack_data1"

int main() {

You can also specify sections for initialized data (data_seg), functions (code_seg), and const variables (const_seg).

Data allocated using the bss_seg pragma does not retain any information about its location.

See /SECTION for a list of names you should not use when creating a section.

See Also


Pragma Directives and the __Pragma Keyword