CMSIS-RTOS2  Version 2.0.0
Real-Time Operating System: API and RTX Reference Implementation
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Thread Stack Management

For Cortex-M processors without floating point unit the thread context requires 64 bytes on the local stack.

Note
For Cortex-M4 FPU and Cortex-M7 FPU the thread context requires 200 bytes on the local stack. For devices with Cortex-M4 FPU and Cortex-M7 FPU the default stack space should be increased to a minimum of 300 bytes.

Each thread is provided with an separate stack that holds the thread context and stack space for automatic variables and return addresses for function call nesting. The stack sizes of the RTX threads are flexible configurable as explained in the section Thread Configuration. RTX even offers a configurable checking for stack overflows and stack utilization.