RTOS/TMS320C6455: Using different memory segments

Part Number:TMS320C6455

Tool/software: TI-RTOS

Hello!
I use TMS320S6455 and SYSBIOS 6.33.5.46. I have two memory segments: .iram_seg and .sdram_seg. By default, or if the heap = NULL, use .iram_seg. I need to be able to use .sdram_seg for some tasks.
In the code of the program, the declaration of .sdram_seg is performed by the line:
xdc_runtime_IHeap_Handle sdram_seg = NULL;

But since NULL is used, iram is used instead of sdram.

How do I get the value for sdram_seg so I can use this memory segment?