CCS: CMD: size is not enough

Tool/software: Code Composer Studio

I define a data group Uint8 buf[8600]. and I met the error:

>> error: can't allocate .stack, size 000a1800 (page 0) in L2RAM (avail:
00020000)
>> error: can't allocate .sysmem, size 000a1800 (page 0) in L2RAM (avail:
00020000)
>> error: errors in input - ./Debug/laneAlgor.out not built

>> Compilation failure

the CMD file is as below:

/*
* Linker command file
*
*/

-stack 0x00001800 /* Stack Size */
-heap 0x00001800 /* Heap Size */

MEMORY
{
L2RAM: o = 0x10800000 l = 0x00020000
DDR2: o = 0x80000000 l = 0x10000000
Flash: o = 0x90000000 l = 0x00400000
}

SECTIONS
{
.bss > L2RAM
.cinit > L2RAM
.cio > L2RAM
.const > L2RAM
.data > L2RAM
.far > L2RAM
.stack > L2RAM
.switch > L2RAM
.sysmem > L2RAM
.text > L2RAM
.ddr2 > DDR2
.buffer > DDR2
}

should I increase heap or stack or change the allocation in section(ex:change all L2RAM to DDR2)